Counterfeit retro games have gone from a curiosity to an industry. Ten years ago a bad repro was obvious across the room. Today the good ones use correct shells, screen-printed labels with the right gloss, and PCBs laid out to match the original. Some are sold honestly as reproductions and then flipped dishonestly two owners later.

The best method

The second-best technique is open it up. The overwhelming majority of counterfeits that pass external inspection fail instantly on the board. Sellers who refuse to photograph the PCB are telling you something.

Universal red flags

These apply everywhere, regardless of platform. None is conclusive alone; two or three together usually settle it.

Listing and seller signals

• The seller has multiple copies of a game with a low print run. Nobody has four loose copies of Little Samson.
• Stock photos, or photos of only the front label. Ask for the back, the connector edge, and the board.
• Price meaningfully below market with no explanation. A 60%-off grail is a fake or a scam, not a find. Check the title against its current loose, CIB and new values before you decide it's a bargain.
• Descriptions that hedge: "for collection," "display copy," "reproduction quality," "not original but plays great," "unofficial." Some of this is honest disclosure buried in fine print.
• Freshly created account, or feedback consisting entirely of low-value items.
• Bulk shipping from regions with known repro manufacturing, especially when the seller has no other retro inventory.

Physical signals

• Wrong screws. This is the fastest single check on most Nintendo platforms and it catches a large share of fakes. Details below by system.
• Label printing. Under magnification, genuine labels from the cartridge era are screen-printed or offset-printed with clean, solid color fields. Most fakes are inkjet or laser output and show a visible dot matrix, halftone rosettes, or slightly fuzzy text edges. Colors read "off", often oversaturated or with a blue-shifted black.
• Label material and finish. Fakes frequently use stock that is too glossy, too thick, or too white. Genuine labels of a given era have consistent finish; a matte-era label that arrives glossy is suspect.
• Label cut and placement. Genuine labels were applied by machine with consistent alignment and corner radius. Hand-applied repro labels drift, have square corners where they should be rounded, or sit slightly proud of the recess.
• Weight. Fakes are commonly lighter, using thinner plastic and a smaller board. Compare against a known copy on a kitchen scale.
• Shell quality. Look at the mold seams, the sprue marks, and any interior text. Nintendo, Sega, and SNK all molded part numbers and date codes into their shells. Recycled genuine shells will have these; freshly molded repro shells often will not, or will have them slightly soft and blurred from a copied mold.
• Smell. Not a joke. Newly molded plastic and fresh adhesive have a distinct chemical smell that a thirty-year-old cartridge does not.

Board signals

Once you have it open, the board is the strongest evidence available.

• Genuine cartridges from the 8- and 16-bit eras use mask ROMs (chips manufactured with the game data burned in at the foundry). They carry the platform holder's own markings: a Nintendo or Sega logo, a licensed part number, a date code, and typically a game-specific code.
• Fakes use generic EPROM, EEPROM, or flash chips from Macronix, Winbond, SST, AMD, Atmel, or similar. A chip with a manufacturer logo that isn't the platform holder's is a very strong indicator, though note that some genuine late-era carts do use licensed third-party silicon.
• Glob-top / epoxy blobs covering a die on a cartridge that should have a packaged chip is a repro signature.
• Hand soldering. Genuine boards were wave or reflow-soldered with uniform, shiny joints. Blobby, dull, or uneven joints, especially around a socket, battery, or added wire, mean somebody worked on it.
• Battery mismatches. A game that never had save memory should not have a battery. A game that did should have one, in the correct footprint, usually spot-welded rather than soldered by hand.
• Board revision codes. Genuine boards carry platform-specific prefixes (listed per system below). A board with no code, or a code that doesn't match any documented revision, is a fake.

Most Atari carts are worth a few dollars, which makes faking them pointless. The exceptions are severe: Air Raid, Birthday Mania, Red Sea Crossing, Gamma-Attack, Karate (Ultravision), and the various rarities from Panda, Zimag, and CommaVid. These sell for four and five figures, and they are faked.

What to check

• Label printing above all. Atari-era labels used specific printing processes and paper stocks. Modern reproductions almost always show inkjet dot patterns under a loupe. Genuine labels also age, so expect some yellowing, edge wear, and adhesive bleed consistent with the rest of the cartridge.
• Shell mold marks. Atari and its licensees each used distinct shells. Air Raid famously used a blue T-handle shell unlike anything else in the library, which is why the fakes concentrate on getting that one shape right. Compare mold seams and interior ribbing to documented examples.
• Board and chips. Genuine 2600 boards use period-correct mask ROMs with date codes in the late 1970s to mid 1980s. A 2600 cart containing a modern EPROM in a socket is a homebrew or repro, not a rarity.
• Screws. Standard Phillips throughout the Atari line, so screw type is not a useful tell here. Go straight to labels and boards.
• Provenance. For any Atari title in the four-figure range, provenance and expert authentication matter more than physical inspection. There are only single-digit known copies of some of these. Buy from established collectors, not from a random listing.

Note on 5200 and 7800: the same logic applies, with even fewer targets worth faking. The 7800's Sentinel and PAL-exclusive titles occasionally attract attention.

The NES has the largest reproduction market of any console.

The screw test

Genuine NES cartridges use a 3.8mm security bit screw ("gamebit"), which has a hollow, splined head. If you see standard Phillips screws, the cartridge has either been opened and reassembled with replacement screws, or it is a reproduction. This single check catches a large fraction of NES fakes because security bits and screws are an extra cost repro makers often skip.

Caveat: legitimate collectors do open carts to replace batteries or clean contacts, and some replace lost security screws with Phillips. Phillips screws mean "investigate further," not "confirmed fake."

Label tells

• Genuine NES labels are matte to semi-gloss, never mirror-glossy.
• The black text and Nintendo Seal of Quality should be crisp at 10x magnification. Fakes show pixelation, especially in the seal's fine lines and small text.
• Look at the spine/end label where present, and at the "NINTENDO" text. Font weight and letter spacing are commonly wrong on repros.
• Genuine labels are recessed flush into the shell. A label sitting on top of the recess, or overlapping its edges, is a repro.

Shell tells

• Genuine shells have "NINTENDO" and a part number molded into the interior plastic, plus a date code.
• Check the cartridge's rear for the molded ridges and the correct dust flap mechanism.
• Grey shell color varies with age and sun exposure, so color alone means little. Still, a shell that is uniformly bright new-plastic grey on a supposedly 35-year-old cart is worth a second look.

Board tells

Genuine NES PCBs carry board codes like NES-NROM-256, NES-SLROM, NES-TLROM, NES-MMC3, and so on, silkscreened on the board. The ROM chips carry Nintendo markings and part numbers matching the game.

Reproductions typically show:

• A generic board with no Nintendo code, or a code that doesn't match a documented mapper for that title
• Flash or EPROM chips (Macronix, SST, Winbond) instead of Nintendo mask ROMs
• A battery added to a game that has no save function, or a hand-soldered battery on a game that should have a spot-welded one
• A donor board from a common game (often Mario/Duck Hunt or a sports title) with a new ROM piggybacked or socketed

Most commonly faked NES titles

• Stadium Events
• Little Samson
• Flintstones: Surprise at Dinosaur Peak
• Panic Restaurant
• Bubble Bath Babes
• Hot Slots
• Peek-A-Boo Poker
• Cheetahmen II
• Bonk's Adventure
• Snow Brothers
• Kid Klown
• Bandai Golf

If you are buying any of these, assume it is fake until the board proves otherwise.

Concentrated on RPGs and late-run titles.

The screw test

Same as NES: 3.8mm security bit. Phillips screws warrant investigation.

Label tells

• Genuine SNES labels have a distinctive semi-gloss finish and a specific black that repros consistently miss. Fakes tend toward a bluish or washed-out black.
• The Nintendo Seal of Quality and ESRB/rating box (on later titles) are where fake printing shows first. Look for soft edges and dot patterns.
• Check label alignment in the recess. Genuine is machine-consistent.

Shell tells

• The two SNES shell variants (the earlier design with the top ridges, and the later revision) should match the title's release window. A launch-window game in a late-revision shell is a rehoused cart.
• Interior molding carries Nintendo part numbers and date codes.

Board tells

Genuine SNES boards carry SNS- (North America) or SHVC- (Japan/international) prefixes, followed by a board type such as SNS-1A3B-11 or SHVC-2A3M-01. ROM chips are Nintendo-marked mask ROMs.

Watch specifically for:

• Save battery behavior. Earthbound, Chrono Trigger, Final Fantasy III, and every other SRAM-save title need a working battery. Many fakes either omit the save circuit entirely or use a hand-soldered battery in a footprint that doesn't match. A cart that appears to save but loses the file on power-off is a classic repro failure.
• Special chips. Star Fox (Super FX), Super Mario RPG (SA-1), Mega Man X2/X3 (Cx4), Yoshi's Island (Super FX 2) all require dedicated coprocessors. Repro makers sometimes recreate these; more often the fake is a donor cart from the same chip family. Verify the coprocessor is present and Nintendo-marked.
• Donor boards. A very common fake pattern is gutting a cheap sports title and reusing its board and shell.

Most commonly faked SNES titles

• Earthbound
• Chrono Trigger
• Final Fantasy III
• Mega Man X3
• Hagane
• Pocky & Rocky 2
• Harvest Moon
• Aero Fighters
• Demon's Crest
• Ogre Battle
• Super Copa
• Wild Guns
• Rendering Ranger R2

The entire late-run Natsume/Nintendo catalog belongs on that list too.

N64 fakes were rare for years because the cartridge format was harder to reproduce cheaply. That is no longer true.

The screw test

Genuine N64 cartridges use a 3.8mm security bit, same family as NES and SNES. Phillips screws are a flag.

Label tells

• Genuine N64 labels are a smooth, low-gloss vinyl-like stock, and they wrap the front recess precisely.
• The Nintendo Seal and rating box are again the first place bad printing shows.
• N64 end labels (on the top edge) are frequently missing or replaced on fakes, or printed on obviously different stock than the front.

Shell tells

• Genuine shells carry molded Nintendo markings and a date code inside.
• Check the dust flap and the plastic's texture. Repro shells often have a slightly different pebble grain.

Board tells

Genuine N64 boards use NUS- prefixes (for example NUS-01, NUS-06). ROM chips are Nintendo-marked. Save-enabled games use EEPROM, SRAM, or Flash RAM depending on the title, and the save chip should match the documented type for that game.

• A repro will typically show a generic board with flash memory and no NUS code.
• Save failure is a very common repro symptom on N64 because the save hardware varies by title and repro boards often implement the wrong type.

Most commonly faked N64 titles

• Conker's Bad Fur Day
• ClayFighter 63⅓: Sculptor's Cut
• Bomberman 64: The Second Attack
• Ogre Battle 64
• Harvest Moon 64
• Worms Armageddon
• Snowboard Kids 2
• Stunt Racer 64
• International Superstar Soccer 2000

This is the worst-affected family, and Pokémon is the worst-affected series in the hobby.

The screw test

The Game Boy line splits, and the split is easy to get wrong. Game Boy and Game Boy Color cartridges use a 3.8mm gamebit (the same security bit as NES, SNES and N64). Only Game Boy Advance cartridges use tri-wing (tri-point Y0). If you brought the wrong bit, the answer is that you brought the wrong bit; it isn't evidence about the cartridge.

On any of the three, a Phillips screw means a repro or a cart that has been opened. Because both gamebits and tri-wing drivers are cheap and widely available now, this test is weaker than it used to be, but it still catches the low-effort fakes.

Label tells: the strongest single check on GBA Pokémon

Genuine GBA Pokémon labels (Ruby, Sapphire, Emerald, FireRed, LeafGreen) use a prismatic/holographic foil with a specific pattern that shifts as you tilt it. Counterfeits either use a flat printed label with a fake "sparkle" texture, a hologram with the wrong pattern or grain direction, or a foil that looks correct straight-on but doesn't shift properly under angled light. Compare against a known genuine copy under a single point light source and rotate the cart.

Across the whole Game Boy line:

• Genuine labels are precisely die-cut and sit flush.
• The Nintendo Seal of Quality is a reliable printing-quality test.
• GBC "dual-mode" cartridges (playable on GB and GBC) have a distinct clear/black shell. Verify the shell type matches the title's documented release.

Shell tells

• Genuine GB/GBC/GBA shells have "Nintendo" and a part number molded on the back, plus a date code.
• GBA shells should have the correct notch profile. GBA carts are keyed differently from GB/GBC.
• On GBA, hold the cart to light: genuine translucent-shell variants (like some Pokémon releases) have specific tint and clarity.

Board tells

Prefixes by platform: DMG- (Game Boy), CGB- (Game Boy Color), AGB- (Game Boy Advance). Mask ROMs carry Nintendo markings.

• Save hardware. Ruby, Sapphire, and Emerald contain an internal CR1616 battery for the real-time clock (berries, tides, Shoal Cave). A genuine copy has one; a fake usually does not, or has a hand-soldered substitute. FireRed and LeafGreen have no RTC battery, so a battery present on those is itself a flag.
• Flash chips. Fake GBA carts almost universally use generic flash (often 32MB flash mapped for multi-game bootlegs) rather than Nintendo mask ROM.
• Solder quality. Genuine boards are cleanly reflowed. Fakes show hand-soldered joints, especially at the battery and cartridge edge.

In-game behavior tests (GBA Pokémon specifically)

• RTC test. On genuine Ruby/Sapphire/Emerald, berries grow and the clock advances in real time. On a battery-less fake, the clock is frozen and the game may display a "The internal battery has run dry" message on boot. Note that a genuine cart with a dead battery shows this too, so it isn't conclusive by itself.
• Save test. Save, power off completely, wait a minute, power on. Fakes lose saves.
• Language and text glitches. Bootleg ROMs are often modified, badly translated, or region-mismatched. Odd capitalization, missing accents, or text overflowing dialogue boxes are strong signs.
• Mystery Gift / link features. Fakes commonly fail link cable and trading functions.

Most commonly faked titles

Every mainline Pokémon release on GB/GBC/GBA, plus:

• Mother 3
• The Legend of Zelda: Oracle of Ages/Seasons
• Fire Emblem: The Sacred Stones
• Final Fantasy Tactics Advance
• Golden Sun
• Metroid Fusion / Zero Mission
• Mega Man Zero series
• Rhythm Tengoku
• Card e-Reader material

Sega's cartridge library has fewer four-figure titles than Nintendo's, which has kept the repro market smaller, but the top of the market is absolutely targeted.

Screws

Genesis/Mega Drive cartridges are normally held by a 4.5mm gamebit security screw, the larger sibling of the 3.8mm bit the Nintendo carts use, so bring both. Sega was far less consistent than Nintendo about this: the shell went through several revisions across the console's life, screw counts and types vary between them, and some carts (many Master System releases especially) are snap-together with no screw at all.

That variation is exactly what makes the screw a weak test on Sega. A Genesis cart with an unexpected fastener is worth a note, not a verdict. Go to the labels and the board.

Label tells

• Genuine Genesis labels vary considerably across the console's life (the early "high-tech" style, the later standardized style). Verify the label style matches the title's release window.
• Sega end labels and spine text are frequently wrong on repros.
• Master System carts used both card-style and standard cart formats depending on region and era. Verify format against documented releases.

Shell tells

• Genesis shells carry molded Sega markings and part numbers.
• Check the cartridge's rear ridges and the tab layout. Region-specific shell shapes (Genesis vs. Mega Drive) should match the label's region.

Board tells

Genuine Sega boards carry 171-xxxx board numbers silkscreened on the PCB, with Sega- or licensee-marked mask ROMs. Repros show generic boards with flash chips.

Most commonly faked Sega titles

• MUSHA
• Crusader of Centy
• Alien Soldier
• Contra: Hard Corps (PAL)
• Mega Man: The Wily Wars
• Pulseman
• Panorama Cotton
• Sonic 3D Blast (PAL variants)
• The Master System PAL-exclusive library

The financial stakes here are the highest in the hobby. Neo Geo AES cartridges routinely sell for hundreds to many thousands of dollars, which makes them the most economically attractive fakes in retro collecting.

What to check

• Board layout and part numbers. Genuine AES boards and genuine MVS boards have different layouts and different SNK part numbers. Know which board revision your target title shipped on. This is title-specific research, and there is no shortcut.
• Chip markings and dates. SNK mask ROMs carry SNK markings and date codes. A conversion will often show mismatched date codes across chips, or chips from the wrong era entirely.
• Added or socketed chips. Conversions commonly require adding a chip or a small daughterboard. Any socket, wire, or piggyback on a Neo Geo board is a serious flag.
• Shell and label. Genuine AES shells have specific molding; labels have specific printing and, on many titles, a particular finish. Fakes have improved a lot here.
• Region. Japanese AES and US AES releases have different labels and, for some titles, different board content. Verify what you're actually buying.

Practical advice: at Neo Geo prices, do not buy from an unknown seller without board photographs, and consider paying for third-party authentication. The community forums that specialize in Neo Geo authentication are the best available resource and are far more granular than any general guide can be.

HuCards are credit-card-shaped and physically simple, which makes them relatively easy to fake compared to a molded cartridge.

What to check

• Card thickness and edge finish. Genuine HuCards have a consistent thickness and cleanly finished edges. Fakes are often slightly thicker or thinner and show rougher edges.
• Printing. Genuine HuCard graphics are printed directly onto the card surface with high quality. Fakes show dot patterns and, frequently, slightly wrong color.
• Contact plating. Genuine gold contacts have even plating. Fakes show thin, patchy, or differently colored plating.
• Region. TurboGrafx-16 (US) and PC Engine (Japan) HuCards have reversed pinouts. They physically fit each other's systems but do not work without a converter. A "PC Engine" card that runs natively on a TurboGrafx is misidentified or fake.
• CD-based titles (TurboGrafx-CD, PC Engine CD, Super CD-ROM²) follow disc rules. See the disc section below.

Frequently faked

• Magical Chase
• Bonk's Revenge
• Dungeon Explorer II
• Air Zonk
• The higher-value Japanese shooters

A note on the shift to discs

Everything from here down is optical media, not cartridges. The tells are completely different: you're no longer inspecting plastic and silicon, you're inspecting pressing quality, hub codes, and label printing.

• Pressed (genuine): the data side has a uniform, mirror-like appearance with a molded inner hub. Around the clear inner ring you'll find stamped alphanumeric matrix/mastering codes and, on most commercial pressings, an IFPI mastering code (typically a small "IFPI" followed by characters, laser-etched into the mirror band) plus an IFPI mould SID code.
• Burned (fake): recordable media has a visible dye layer (silver-purple, blue, or greenish depending on the disc) and no stamped matrix codes. A CD-R or DVD-R has a distinctly different look and often a visible "burn ring" where the recorded area ends.

The black disc test

Genuine retail PS1 discs have a black-tinted data side. This was Sony's deliberate anti-piracy measure. A PS1 disc with a normal silver, blue, or purple underside is a burned copy. The exception is some genuine promotional, demo, and press discs, which were occasionally silver. For retail games, black is what you expect.

Other checks

• Hub codes. Genuine discs have stamped matrix codes and an IFPI code in the mirror band.
• Label printing. Genuine PS1 disc labels are screen-printed with sharp text and correct Sony logos. Printed paper labels stuck to a disc are conclusive: fake.
• Case and inserts. Genuine PS1 jewel cases have the correct rear J-card, spine text, and manual print quality. Fakes often have a photocopied manual or a color-shifted cover.
• Ring codes matching the region. A NTSC-U game with a PAL ring code, or vice versa, is a rehoused disc.

Frequently faked

• Suikoden II
• Valkyrie Profile
• Persona 2: Eternal Punishment
• Tomba!
• Klonoa
• Rhapsody
• Misadventures of Tron Bonne
• Symphony of the Night (specific variants)
• Jade Cocoon

Most Working Designs and Atlus releases belong on that list as well.

Saturn (CD)

Genuine discs have a silver data side with stamped hub codes and Sega/manufacturer markings. Applied paper labels or dye-visible recordable media are conclusive fakes. Saturn's high-value library (Panzer Dragoon Saga, Radiant Silvergun, Burning Rangers, Dragon Force, Shining Force III) attracts consistent counterfeiting, usually as burned discs in reproduced cases.

Dreamcast (GD-ROM)

This one is unusually easy. Genuine Dreamcast games shipped on GD-ROM, a proprietary 1GB format that consumer hardware cannot write. A Dreamcast disc that is a standard CD-R is definitionally not a retail release. Genuine GD-ROMs have a distinctive appearance with the characteristic dual-density data area and Sega's markings around the hub. Because Dreamcast piracy was rampant in the console's own era, a lot of burned discs in genuine-looking cases are circulating.

Especially on late-run and low-print titles.

Disc format checks

• Genuine PS2 games ship on either a blue-tinted DVD (earlier and single-layer titles) or a silver dual-layer DVD (later, larger games). Which one is correct depends on the specific title, so verify against a known release listing rather than assuming.
• Genuine discs have stamped matrix and IFPI codes in the inner mirror band.
• Genuine labels are screen-printed with a holographic PlayStation 2 logo on many releases. Check that it's part of the printed label, not a sticker.
• A DVD-R with a printed paper or inkjet-printable label surface is a fake.

Other checks

• Case artwork. PS2 cases use a specific plastic and a full-wrap insert. Reproduction covers are common; check for correct barcode, ESRB placement, and print sharpness.
• Manual. Genuine manuals are printed on specific stock with correct binding. Photocopied or laser-printed manuals are the giveaway on "complete" copies.
• Burned backup discs. Many PS2 owners in the era ran modchips and burned backups; a burned disc in a genuine case is extremely common.

Frequently faked

• Rule of Rose
• Haunting Ground
• Kuon
• Suikoden III / V
• .hack series
• Shadow Hearts series
• Persona 3 FES
• Xenosaga series
• God Hand
• Gitaroo Man
• Ico & Shadow of the Colossus variants

PS3 games shipped on Blu-ray, which is expensive and technically difficult to replicate at counterfeit scale. As a result, genuine-looking fake PS3 discs are rare compared to earlier generations. Packaging is another matter.

What actually gets faked on PS3

• Cases and inserts. This is the real problem. Reproduction cover art, reprinted manuals, and fake slipcovers/sleeves are common, especially on limited and collector's editions where the packaging carries most of the value.
• Slipcovers and special-edition packaging. A genuine disc in a reproduced slipcover, sold as a complete limited edition, is the standard PS3-era misrepresentation.
• Sealed copies. Resealing is the dominant fraud at this end of the market. See the sealed-game section below.

What to check

• Genuine PS3 discs have a holographic/reflective printed label with sharp Sony branding and correct region text, plus stamped hub codes.
• BD-R recordable media has a visibly different data surface and no stamped matrix codes.
• Compare slipcover print quality against a known genuine copy. Reproduction slipcovers frequently show slightly soft type, wrong cardstock weight, and incorrect spot-gloss or foil treatment.
• Verify the disc's printed title, region code, and part number match the case artwork. Mismatches mean the copy was assembled from parts.

Sealed and graded games: a separate problem

Everything above assumes you can inspect the item. Sealed games invert the entire process, and the fraud shifts from the game to the wrap.

Resealing is the primary risk

Professional resealing equipment is cheap and widely available, and a resealed game can look better than a genuine 30-year-old seal. Key checks:

• Seam placement and count. Factory shrink wrap for each publisher and era has a characteristic seam pattern: where the seams fall, how many there are, and how the corners fold. Resealed games often have seams in the wrong place or extra seams.
• Wrap material. Period-correct wrap has specific thickness and gloss. Modern wrap is often thinner, clearer, and shrinks tighter than the original.
• Hangtabs and factory features. Many NES, SNES, and Genesis releases have hangtabs, sealed stickers, or factory-applied price stickers whose presence and style should match the print run.
• Y-folds and end folds. The way the wrap terminates at the ends is era- and factory-specific.
• Yellowing consistency. Genuine old wrap yellows; new wrap doesn't. Wrap that looks newer than the box beneath it is a flag.

Grading is not authentication, exactly

WATA and VGA slabs raise the bar considerably, but they are not infallible, and slab tampering and counterfeit slabs both exist. Verify the certification number against the grader's own database, check the slab for tampering at the seams, and be aware that a slab tells you what a grader concluded on one day, not a guarantee.

Quick reference: screws by platform

A cheap set covering the 3.8mm and 4.5mm gamebits plus tri-wing costs under $15 and pays for itself the first time it saves you from a bad purchase. The 4.5mm bit is the one people skip. It is the Genesis cartridge size, and it opens most consoles of the era too.

Quick reference: board code prefixes

A board with no prefix code, or a code that doesn't correspond to a documented revision for that title, is the strongest single indicator of a reproduction.

A five-minute inspection routine

If you're at a swap meet or a store and have one shot at this:

1. Weigh it in your hand against a known-genuine cart from the same system.
2. Check the screws. Wrong type on a Nintendo platform is an immediate flag.
3. Angle the label to a light. Look for dot patterns, wrong gloss, misalignment, and soft edges on the Seal of Quality.
4. Look at the shell interior markings through the cartridge opening if you can't open it. Some molding is visible from the connector edge.
5. Ask to test it. Boot behavior, save function, and (on GBA Pokémon) the real-time clock will catch a large share of fakes.
6. If it's a high-value title, ask to open it. A seller confident in their item will allow this. One who won't has told you what you needed to know.

When you're wrong anyway

Even careful collectors get caught. If you buy a fake:

• Document everything with photos before you contact the seller, including the board.
• Most major marketplaces have buyer protection covering counterfeit items, and counterfeit claims are typically treated more seriously than ordinary "not as described" disputes. File under the counterfeit category specifically.
• Report the listing. The single most effective thing the collecting community does about repro fraud is remove sellers from the marketplaces.
• Don't resell it as genuine. That's how most fakes end up in circulation: not from the original counterfeiter, but from a burned buyer trying to recover their money.