15. "Elemental Gearbolt" Assassin’s Case (PS1): $1,400-$1,750
"Elemental Gearbolt" is a Japanese sci-fi shooter released for the original Playstation in 1997.
The Assassin's Case was awarded during a 1998 E3 tournament, and only 40 of these limited-edition bundles were produced. The case includes the "Elemental Gearbolt" game and a golden "GunCon" and memory card.
14. "Eli’s Ladder" (Atari 2600): $1,500-$1,700
"Eli's Ladder" is the rarest educational video game in existence.
Players answer simple math questions to move Eli up the ladder and into his spaceship, all so he can fly to the moon. The game even includes a wall chart and motivational stickers, according to RacketBoy.
13. "Karate" (Atari 2600, Ultravision release): $2,500-$4,000
"Karate" for the Atari 2600 was designed by black belt Joseph Amelio. The game was actually released by two publishers, Ultravision and Froggo.
The Ultravision version, released first in 1982, is far more valuable than the Froggo release, though the games are exactly the same.
12. "Gauntlet" (Atari 2600): $3,000-$5,000
"Gauntlet" allows players to control Sir Robert Whittenbottom as he runs a tribal gauntlet in attempt to be welcomed into their ranks.
Interestingly enough, "Gauntlet" was a mail-order game that didn't even have traditional packaging. Instead, the game would arrive in a foam case.
11. "Tetris" (Sega Genesis/Megadrive): $3,000-$16,000
Due to legal issues and Nintendo's exclusive rights to "Tetris" on video game consoles, the Sega Genesis (or Megadrive) never saw a "Tetris" game released.
The unlicensed version was recently confirmed to exist by none other than "Tetris" creator Alexey Pajitnov (pictured). RacketBoy estimates around 10 copies of "Tetris" for Sega Genesis exist today.
10. "King of Fighters 2000" (Neo Geo): $3,540-$6,000
A competitive fighting game, the English edition of "King of Fighters 2000" pits Commander Heidern against the evil NESTS cartel.
With only 100 confirmed copies in the wild, "King of Fighters 2000" is the last in the series produced by publisher SNK before their bankruptcy.
9. "Ultimate 11/Super Sidekicks 4" (Neo Geo): $4,800-$10,000
A favorite of sports fans with a Neo Geo game console, the "Ultimate 11" European version is widely considered the last true standalone game in the series.
The original "Super Kicks," released in 1993, was the first soccer game for the Neo Geo system.
8. "Atlantis II" (Atari 2600): $5,000-$18,000
In this Atari game, players must protect the city of Atlantis from the evil Gorgon spaceships. A beefed-up take on the original "Atlantis" game, "Atlantis II" features harder gameplay and a competition-tuned scoring system.
Winners of the "Defend Atlantis" competition were sent copies of "Atlantis II." RacketBoy reports that the four finalists were flown to Bermuda for the ultimate showdown, with the winner receiving $10,000 in prize money.
7. "Kizuna Encounter" (Euro): ~ $5,400-$13,500
The European release of "Kizuna Encounter" is a somewhat mythical game. There are only five claimed sales in the past.
You can find this fighting game at arcades, however, and the Japanese release is far more common. The mysterious and tough-to-trace European production run of "Kizuna Encounter" has led to sales that RacketBoy reports "supposedly ended in the range of $12,000-$13,500."
6. "Red Sea Crossing" (Atari 2600): $10,400-$14,000
Promising players the chance to experience Moses' Biblical crossing of the Red Sea, there were only 100 of these cartridges produced. So far, only two have been found in the wild.
5. 1991 Nintendo Campus Challenge (NES): $14,000-$20,100
Composed of "Super Mario 3," "PinBot," and "Dr. Mario," this Nintendo NES cartridge was used for Nintendo's campus gaming competitions. Though all copies were thought to be destroyed, RacketBoy reports that a copy was found in the garage of an ex-Nintendo employee.
It was sold for $14,000 in 2006 and resold for $20,100.
4. "Air Raid" (Atari 2600): $14,000-$33,400
"Air Raid" sports a blue cartridge with a unique T-shaped handle. The purpose of the game is to defend the city from an air raid using your own aircraft.
According to RacketBoy, only 12 copies of the game are rumored to exist. Two copies of "Air Raid" have sold recently for $14,000 and $33,400 on eBay and gaming auction site GameGavel.
3. 1990 Nintendo World Championships: Gold Edition (NES): $15,000-$21,000
There are only 26 copies in existence of this gold-colored limited edition cartridge. The 26 cartridges were awarded to the winners and runner-ups of Nintendo's Power contest.
The game itself consists of a customized combination of "Super Mario Bros," "Rad Racer," and "Tetris," all with a special tournament timer ticking away.
2. "Birthday Mania" (Atari 2600): $15,000-$35,000
With only one verified copy in existence, "Birthday Mania" is one of the rarest games of all time.
"Birthday Mania" allows players to play mini games consisting of popping balloons and blowing out candles. It also comes in a box that allows you to personalize it with a birthday message or name.
1. "Gamma Attack" (Atari 2600): $20,000-$50,000
This Atari 2600 game is arguably the rarest video game available.
Only one cartridge was produced by gaming company Gammation, and it currently is owned by collector Anthony DeNardo, according to RacketBoy. DeNardo has listed the cartridge on eBay before, asking a $500,000 Buy-It-Now price.