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 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:

• MVS to AES conversions are generally uncommon in the modern market. 

• Most MVS to AES conversions done by modern modders (like Neotropolis) are advertised as such - and are woefully overpriced.

• True conversions typically only exist for the more outrageously priced AES games like Kizuna Encounter or Metal Slug. You won't often find conversions for common titles under $500 or so.

• Playmore era games (2001-2004) generally cannot be converted (or are very hard to do).

• There are some games, like Metal Slug X, that cannot be easily converted from MVS to AES due to an Altera Max chip included on the PCB for security.

• Ask yourself these questions: Should I just get an authentic MVS game and compatible converter? How much do I actually care about an AES game form factor in these games? If I'm willing to get a true conversion, would I just be better off getting a reproduction? 

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. 

• Due to the abundance of Japanese AES games compared to US/Euro releases, the much more common Japanese variants are the ones most commonly used for modern conversions. 

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!

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. 

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 an 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. 

• Ninja Master's is the only Neo-Geo game that's 330 mega bits - the theoretical limit of Neo games that is emblazoned on the console's shell. So, let's use that as our baseline game. 

  • Weight: 14.7oz

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

• Real Bout Fatal Fury is 346 mega bits. Slightly larger than Ninja Master's.

• These two games use the same PCB's, but Real Bout has one more Mask ROM on its PROG board that will make it a bit heavier. 

• Weight:14.8oz

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

• I have an EPROM conversion of Twinkle Star Sprites that weighs 1.17lb that uses the same PROG and CHA boards as the prior two games but has an ever smaller memory footprint - by more than half!

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. 

Reproductions are a fair bit lighter than an authentic game, and much, much lighter than an EPROM conversion due to the weight of newly manufactured PCBs that do not use multiple ROM chips. Reproductions are a great way to pad your AES 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 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.