 | U.N. Defense Force: Earth Joker | 1993 | Visco | earthjkr | Shooter / Flying Vertical | 8.50 |
 | U.N. Squadron (USA) | 1989 | Capcom / Daipro | unsquad | Shooter / Flying Horizontal | 6.37 |
 | U.S. Championship V'ball (bootleg) (clone of: vball) | 1988 | bootleg | vballb | | 0.00 |
| U.S. Championship V'ball (Japan) (clone of: vball) | 1988 | Technos Japan | vball2pj | Sports / Volleyball | 0.00 |
| U.S. Championship V'ball (US) | 1988 | Technos Japan | vball | Sports / Volleyball | 9.50 |
 | U.S. Classic | 1989 | Seta | usclssic | Sports / Golf | 0.00 |
 | U.S. Navy (Japan 901012) (clone of: cawing) | 1990 | Capcom | cawingj | Shooter / Flying Horizontal | 0.00 |
 | Ufo Senshi Yohko Chan (MC-8123, 317-0064) | 1988 | Sega | ufosensi | Maze / Shooter Large | 0.00 |
| Ufo Senshi Yohko Chan (not encrypted) (clone of: ufosensi) | 1988 | bootleg | ufosensib | | 0.00 |
 | Ultimate Ecology (Japan 931203) (clone of: ecofghtr) | 1993 | Capcom | uecology | Shooter / Flying Horizontal | 0.00 |
| | Ultimate Mortal Kombat 3 (rev 1.0) (clone of: umk3) | 1994 | Midway | umk3r10 | Fighter / Versus | 0.00 |
| | Ultimate Mortal Kombat 3 (rev 1.1) (clone of: umk3) | 1994 | Midway | umk3r11 | Fighter / Versus | 0.00 |
| | Ultimate Mortal Kombat 3 (rev 1.2) | 1994 | Midway | umk3 | Fighter / Versus | 8.62 |
 | Ultimate Tennis | 1993 | Art & Magic | ultennis | Sports / Tennis | 3.50 |
| Ultimate Tennis (v 1.4, Japan) (clone of: ultennis) | 1993 | Art & Magic (Banpresto license) | ultennisj | | 0.00 |
 | Ultra Balloon | 1996 | SunA | uballoon | Platform / Run Jump | 10.00 |
 | Ultra Maru-hi Mahjong (Japan) | 1993 | Apple | ultramhm | Tabletop / Mahjong *Mature* | 0.00 |
 | Ultra Tank | 1978 | Atari | ultratnk | Shooter / Versus | 6.00 |
 | Ultra Toukon Densetsu (Japan) | 1993 | Banpresto / Tsuburaya Productions | utoukond | Fighter / 2.5D | 7.67 |
 | Ultra X Weapons / Ultra Keibitai | 1995 | Banpresto / Tsuburaya Productions | ultrax | Shooter / Flying Vertical | 8.14 |
