Conversions & reproductions

Author: M.E. Williams

It's no secret that the Neo-Geo hardware has seen one of the more explosive bootleg markets in all of video games. That said, it's also no surprise given the high cost of owning authentic games on the AES, and even some MVS games. While there are bootlegs of NeoCD games (given the hardware has no copy protection built in), the AES and MVS are where the money is. It's in this market segment that we see the vast majority of bootlegs in the modern Neo-Geo Market.

The word "conversion" has become a modern catch-all in the Neo-Geo market that includes three types of bootlegs: 

This confusing catch-all can cause undue hardship on the new Neo-Geo collector who does not yet have the market savvy to know what they are purchasing. 

While many collectors look down upon any type of "conversion", many buyers flock to these bootlegs due to the generally lower bar of entry to having some of the most sought after games. Given the gulf in prices between the AES and MVS, one could easily come to the conclusion that if you want to save money on authentic games just get the MVS versions. While that sounds good in theory, bootlegs are synonymous with the MVS market and buyers need to be even more scrupulous when purchasing games in that segment.

Purchasing a conversion or a reproduction isn't the end of the world, and unless you have some self-inflicted morality on what should be done with retro video games, they can save you a lot of money up front. Just be advised that you won't make any money in the long term as they have no investment potential. 

MVS to AES conversions

These are the true conversions - where the authentic mask-rom chips are desoldered from MVS PCBs and resoldered onto a compatible, authentic AES PCB. While the final product uses all authentic parts, it does sacrifice the original AES and MVS games - which is a big problem for some people. For others, this is a great way to get 100% compatible games for a fraction of the cost. 

My example photo, Neo Bomberman, is a true conversion. This game also never had an official AES release. 

MVS to AES conversions are contentious in the Neo-Geo community due to the sacrifice of two authentic games to create one mostly authentic game. On one hand it is understandable that those passionate about these second-hand consumer products want to protect these authentic pieces from being defaced, destroyed, or otherwise ruined. On the other hand (and I don't mean to sound flippant), unless these people who have a moral objection to conversions want to pony up the cash to purchase all games that are at risk of being a sack cart, there really isn't a whole lot to do about this situation. It's your money, so spend as you see fit.

When deciding what side of the fence you are on, here's a few things to consider:

How are Conversions Made?

Contrary to popular belief, you can't just convert any game to a new one. Over the years SNK used different PROG and CHA (the PCBs inside of Neo cartridges) boards that have different memory configurations. For example, Fatal Fury and many other early Neo games use boards called 42G1. Unless you want to make a bootleg of Legend of Success Joe, these early cartridges aren't often used for conversions.

The most compatible boards for sought after games like Metal Slug, Ninja Master's, Twinkle Star Sprites, etc. are the ones used in Fatal Fury 3, Real Bout, and Samurai Shodown 3. These are the BK1 and 256 board variants. These games are still so widely available in circulation that using these games as sacrifice games for conversions has generally not affected their value in the market. 

That said, real conversions are also not all that common in the modern market due to the wide market availability and easy manufacture of reproduction cartridges and EPROM conversions. And many EPROM converts and Reproductions are so close to the original, sellers can often get away with selling you a very convincing bootleg!

Image Credit: 

How do you know if the Mask ROM is legit? 

All Neo-Geo cartridge games, either AES or MVS, have the NGH number (SNK's production code system for their games) stamped on the Mask ROMs. Some of these chips will have a brand on them, like Toshiba, but some wont. The thing to look for is the actual production code for the game printed on each chip. 

For example, the image from you see here is from Alpha Mission 2, which has an NGH production code number 007. You can see this number on every chip on this PROG board. The chips on the daughter CHA board will also have the NGH number for the game. 

There are some caveats, like SNK made upgrades where you'll see a couple different production codes on different chips (like in the case with Fatal Fury 3 and Real Bout Fatal Fury). By and large, though, this is a sure fire way to at least tell if the chips are legit.

At the end of the day you will need to make your own choice on the ethics behind purchasing a conversion. Just make sure you are making a choice that is congruent with your views, values, and what you want out of your collection. It's your collection and money to spend, so make sure you're not making a choice just to please some know-it-all collector on the internet. Some people have very strong opinions about conversions. 

If you want to purchase a conversion keep in mind that they typically do not rise in value - these are essentially bootlegs after all. Reselling a conversion in the market will often result in a loss for you, so only purchase a conversion if you plan on keeping it. While you can also get scalped by people selling conversions as authentic games (this doesn't happen as often as you'd think), what you need to look out for is overpaying for conversions. 

You will also want to check to make sure the "conversion" is an MVS to AES true conversion as many merchants will sell you a reproduction or EPROM conversion and call it an MVS conversion - phew, that's a lot of conversion. Because of this catch-all word, people often are unaware of what they are purchasing. The only way to check what you're buying is if the seller provides pictures of the boards and you can verify the mask-rom chips on MVS Scans to ensure authenticity. 

EPROM Conversions

These conversions sacrifice only one AES game by removing the authentic mask-roms and replacing them with programed EPROMs containing data from a different game. EPROMs are essentially a silicon CD-R - these are blank slate chips that can house any type of data. They can also be erased and re-written.

The example picture is from an EPROM conversion of PULSTAR.

EPROMs have some drawbacks, like a shorter shelf life than mask roms. But because of their versatility, they have been used across the decades as bios chips for various types of computers, among other uses. There are even some EPROM chips used in tandem with Mask ROM chips in authentic versions of Neo-Geo games (like some revisions of Art of Fighting 2, for example) when SNK would make a last-minute update to the game's code. 

You can easily spot the difference between a Mask ROM and and EPROM due to a little window on the top of the chip. If a UV light is shone on the window it will erase the contents of the chip. You'll often see EPROM chips with a piece of electrical tape over the window to protect it from UV rays. While the data on these chips will eventually deteriorate over time, they will last between 20-30 years - much longer than the amount of time you'll most likely use the game.

It's All in the Weight:

EPROM conversions are quite a bit heavier than authentic games/conversions. Without opening up a game, just compare the weight. If you have a simple kitchen or postal scale this becomes even easier. 

Weight will be different depending on the board/Mask ROM configurations, so not all boards will weigh the same. For example:

An EPROM conversion will more than likely weigh close to or over 1 pound due to the weight of the EPROM chips. 

While this not an exact science, you can use this scale as your baseline. Of course some early games, like Fatal Fury 2, weigh in less than 14oz - but these will still be heavier than a reproduction (see below) and much lighter than an EPROM conversion. EPROM conversions are also the most glitch prone. If one of the chips was not programed correctly it can cause numerous issues. It won't ruin your hardware, but the game may become unplayable. If you purchase an EPROM conversion, make sure you aren't paying much. 


This "conversion" uses 100% all new parts and newly manufactured PCBs of varying quality. Collectors don't care much for reproductions, as they are worthless in the market, but still cost quite a bit to produce for the boutique sellers that make them. Expect to still pay over $200 for reproductions of any type. 

Image Credit: Culturea Neo-Geo

Reproductions are a fair bit lighter than an authentic game, and much, much lighter than an EPROM conversion due to the lighter weight of newly manufactured PCBs that do not use multiple ROM chips. Reproductions are a great way to pad your AES or even MVS collection if you want some of the more expensive games to play on your console. As they do not sacrifice any authentic games in their creation, if you have a moral dilema with conversions, this is your only other option to keep prices down. NCI is a popular reproduction manufacturer for AES games, and NeoOldStore is another. If you're after reproductions I do recommend NeoOldStore. Their reproductions are a fair amount cheaper than NCI and are the same or better quality. They advertise as "conversions", but most of their games are repros and can be had for less than $250 no matter the game.

You can also get multi-game reproductions. The 161-in-1 cartridge is a very popular choice, but you can also get single cart series collections. Having all the Metal Slug or Samurai Shodown games on one cart is a great way to save money and even reduce wear and tare on your hardware from constant game switching. 

Reproduction materials

There is also a market for reproduction cases, manuals, inserts, and cartridge stickers. While these are around mostly for the reproduction game market, savvy buyers can also customize their game collection with these pieces - or buyers like me that source loose cartridges can get a reproduction case and insert in order to store and protect my investments.

This copy of Last Resort, for example, has an authentic game and manual, but the case and case insert are reproductions.

Reproduction softbox cases are just a tiny bit larger than authentic, and don't quite smell the same, but are otherwise a fair representation of the originals. Snaplock case reproductions use more matte plastics and the edges along the spine are white instead of black due to how they are hinged. Unless you know what to look for, though, it's hard to tell the difference between these cases and an authentic. Authentic inserts, labels, and manuals use a type of printing called "off-set." Reproduction printed material use high quality, laser prints. While these generally do look great, they are not quite the quality of an original but can come very close. 

Authentic snaplock - sheen corner and rounded edges.
Bootleg snaplock - matte corner and flatter design.
Authentic snaplock spine - black crease and stiff open.
Bootleg snaplock spine - white crease and loose open.
Authentic snaplock inside.
Bootleg snaplock inside.
Authentic vinyl inside.
Bootleg vinyl inside.

What should you do?

At the end of the day, do what you want with your money. If you want to collect for the Neo-Geo you have to do it within your own budget. Conversions and reproductions come with savings, but also with numerous caveats that I hope I've done a good job explaining to you. 

Personally, I don't have a problem with conversions or reproductions. The AES game form factor is important to me because of my nostalgia with that piece of hardware. Over the last 25 years I've owned two MVS set-ups (both an arcade cab and a supergun + MVS board set), and I've sold both of those set-ups twice to switch back to AES. As a long-time collector, authenticity is important to me. And while I typically purchase MVS versions of games when an AES version is out of my price range, there are a few conversions that have snuck into my meticulously curated library. :)