The Neo Geo Pocket was a powerful handheld in a very small package, but never really challenged the Nintendo Gameboy for the market. A black and white version was originally released, shortly followed by a colour version. The games are compatible with both. My unit is the black and white version, which I picked up for 10 quid from

Games OwnedBoxedInstructions
Dark Arms: Beast Buster
Metal Slug: 1st Mission
Neo Turf Masters
Puzzle Bobble Mini
Games AvailableSourcePrice
BioMotor Unitron
Crush Roller
Dive Alert
Fatal Fury: First Contact
Gals Fighter
King of Fighters
Magical Drop
Metal Slug: 2nd Mission
Neo 21
Neo Cherry Master
Neo Dragon's Wild
Neo Mystery Bonus
Neo Geo Cup '98 Plus
Pocket Tennis
Puyo Pop
Puzzle Link
Puzzle Link 2
Samurai Showdown 2
Shanghai Mini
SNK vs. Capcom: Card Fighters Clash (Capcom)
SNK vs. Capcom: Card Fighters Clash (SNK)
SNK vs. Capcom: The Match of the Millennium
Sonic the Hedgehog