As some of you know, the buying and selling of rare video games has become more popular over the years with hard-to-come-by titles fetching upwards of $20,000. While there are highly valuable and sought after games from many of the vintage gaming systems of the past, many of the rarest gems come from the Atari 2600.  

Originally called the Atari VCS, the 2600 has garnered an iconic status among gamers in the nearly 40 years since its original release back in September of 1977. There a huge number of now very low cost titles that were made for the console, but there are also a few extremely valuable ones. 

There were only 100 cartridges of Red Sea Crossing produced and complete copies have an estimated value of between $10,000 and $14,000. Another extremely rare title is Air Raid, with only two known in existence, the oddly shaped blue cartridge has sold for $14,000 and $33,400 on eBay and the game auction site GameGavel.

On top of a few other valuable titles in the $18,000 to $35,000 range like Atlantis II and Birthday Mania (only 1 copy verified to exist), the rarest and most expensive title for Atari 2600 (or any console for that matter) is Gamma Attack. Some reports suggest only one copy was produced and other suggest a handful, but either way there is only one known copy in existence. The best estimates on this title put it at a value between $20,000 and $50,000, making it arguably the most valuable game in history.

Some other extremely valuable games come from the NES and Neo Geo libraries as well like the well known Nintendo tournament cartridges. With 26 of them awarded to the winners and runner-ups of a Nintendo Power contest, 1990 Nintendo World Championships: Gold Edition, which has tournament versions of Super Mario Bros, Tetris and Rad Racer, has an estimated value of between $15,00 and $21,000. Another Nintendo tournament cartridge, 1991 Nintendo Campus Challenge, which contains Super Mario 3, PinBot and Dr. Mario went for $20,100 in 2006.

Some other notable mentions include an unreleased Genesis title and a couple rare NeoGeo games: Ultimate 11/Super Sidekicks 4 for at up 10 $10,000 and King of Fighters 2000 has a value of as much as $6,000. Sega Genesis never actually saw an official release of Tetris but the game's creator has since confirmed the existence of Tetris for Sega and there are only about 10 out in the wild at an estimated value of between $3,000 and $16,000 a piece, according to reports.