6. "Kizuna Encounter"
Format: SNK Neo Geo
Highest price ever paid: $10,000

See if you can follow this series of caveats to a big game payday.
 
SNK made a ton of fighting games, including "Samurai Showdown" and "King of Fighters," but "Kizuna Encounter" was basically its "Mortal Kombat" or "Street Fighter I" when it was released in 1996: It was the sequel to a game called "Savage Reign" and players could tag characters in and out of a fight, similar to games in the popular "Marvel vs. Capcom" series.

It's brilliant, but it's not always worth much of anything. The arcade version is still widely available here in the U.S. and sells for about $50, or 75% less than its original price. The Japanese home version of the game is also pretty easy to come by and won't cost a buyer much.

The real money's in the European home version of "Kizuna Encounter," which is absolutely identical to the Japanese version in every way except its packaging and instructions. That's right: You're paying thousands of dollars for English-language packaging on a game you can pick up without breaking a $100 bill here in the states.

Welcome to video game collecting, where minutiae pay big.

5. "Super Sidekicks 4: Ultimate 11"
Format: SNK Neo Geo
Highest price ever paid: $10,000

Generally speaking, sports games just don't increase in value.

That copy of "Madden NFL '13" gamers just shelled out $60 for last month will be worth a third of that or less by this time next year. Rules change, features change, players change, but the sports game maker's prime directive never changes: Squeeze 'em for every dime.

"Super Sidekicks 4" broke that mold in 1996 not because it did anything particularly clever by letting players use one of 80 national teams to compete for the world soccer title, but because it made the game in such limited supply. The console had a decade's worth of life left in it, but for reasons unknown SNK decided not to make too many versions of a game showcasing the world's most popular sport. As a result, this game is really hard to find and is valued at close to five digits whenever it appears.

4. "Nintendo PowerFest 94"
Format: Super Nintendo
Highest price ever paid: $12,000

Nintendo loved gaming competitions, and its super-sized PowerFest conventions were great places to hold them.

When it came time to hold its competition in 1994, Nintendo made 30 cartridges containing playable portions of "Super Mario: Lost Levels," "Super Mario Kart" and "Ken Griffey Jr. Baseball." Each player had six minutes to get a high score, and the top scores were invited to San Diego for the finals.

The cartridges weren't supposed to survive the festival, but two distinct copies did: one from the preliminaries and one from the finals. The last time a copy changed hands, back in July, it did so for $12,000. That's basically how much you can charge when there are no other options on the table.

3. "Stadium Events"
Format: Nintendo Entertainment System
Highest price ever paid: $14,890

Again, little differences make a big difference when game prices get up this high.

Bandai's "Stadium Events" was released in North America in 1987 and designed to go with Bandai's Family Fun Fitness mat peripheral for the Nintendo Entertainment System. Nintendo loved Bandai's idea so much that it bought the North American rights for the mat and renamed it the Power Pad.

The rebranding meant that all its "Stadium Events" games in North America with allusions to the Family Fun Fitness mat needed to get sent back and rereleased as Nintendo's "World Class Track Meet." That didn't go as smoothly as Nintendo would have liked, and 200 copies of "Stadium Events" with the original branding made it to market. As many as 20 still-wrapped copies exist today, but buyer beware: European copies of the game are far less rare and look almost identical to the hard-to-find North American version.

2. "Nintendo World Championships"
Format: Nintendo Entertainment System
Highest price ever paid: $11,500 for the gray cartridge, $18,000 for the gold cartridge

How big a deal was Nintendo in 1990? Not only was it hosting its first-ever video game competition, but it also basically used a feature-length film called "The Wizard" as an infomercial for it a year earlier.

The artistic merit of Fred Savage, Christian Slater and future Rilo Kiley frontwoman Jenny Lewis shilling for a video game console is still debatable, but the value of the games left over from that first competition certainly isn't.

Nintendo loaded up 90 or so cartridges with playable snippets of "Super Mario Brothers," "Rad Racer" and "Tetris" and gave players six minutes to rack up the highest score. After the competition ended, Nintendo fan magazine Nintendo Power gave away 26 gold-colored versions of the same cartridges as part of a promotion.

Nintendo gave away 90 gray versions of the cartridge, but collectors believe there may be more. The gold cartridges, however, dwindled from 26 to just the 13 known today. Were they thrown out by mean parents who just had to have that extra quarter-inch of space in their empty-nest attic? Were they abandoned in basements by uncaring kids who forgot all about them once puberty hit? Are they just being hoarded by that kid from grade school who never gave back any of the games you traded for, leaving you with oxidized versions of "Duck Hunt" and "Bubble Bobble"?

We don't know, but consider them 13 golden tickets every member of Gen X should search for when they're back at the folks' place this holiday season.

1. "Nintendo Campus Challenge '91"
Format: Nintendo Entertainment System
Highest price ever paid: $20,100

Before Sundays spent playing "Madden" in a suite's common room or reading days wasted picking off dorm mates in "Goldeneye," there was Nintendo's "Campus Challenge."

Back in 1991, Nintendo went to to college campuses across America with 30 special cartridges that gave players six minutes to rack up a high score on "Super Mario 3," "Pin-Bot" and "Dr. Mario." If students could fight through fatigue, hunger or ADD long enough to produce their school's best score, they moved on to a national competition.

Apparently, though, some notoriously sticky-fingered students came away with parting gifts. Nintendo supposedly destroyed all the competition's cartridges, but one was found at a garage sale in New York. It has been sold to several different collectors, with the highest recorded price being $20,100. If that cartridge survived, that means someone else's old roommate may have swiped one during a moment of clarity. Time to drop some queries to your old classmates on Facebook. Don't accept "Dave's not here, man" as an answer.

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