| 8518 | Ollie Octopus' Sketchpad | ZX-Spectrum 16K | English |
| 40944 | Olympia | ZX-Spectrum 16K | English |
| 26933 | Omega Invaders | ZX-Spectrum 16K | English |
| 16963 | On-Error-Goto | ZX-Spectrum 16K | English |
| 34701 | One Kick | ZX-Spectrum 16K | English |
| 39402 | One Line Snake | ZX-Spectrum 16K | Multi-language: English, Spanish |
| 27510 | OpenSE BASIC | ZX-Spectrum 16K | English |
| 26934 | Opening Up Graphics | ZX-Spectrum 16K | English |
| 44715 | Operation Bee | ZX-Spectrum 16K | English |
| 42517 | Operation Skyd Bismarck | ZX-Spectrum 16K | Danish |
| 31438 | Optical Illusions | ZX-Spectrum 16K | English |
| 18388 | Orbit | ZX-Spectrum 16K | English |
| 3540 | Orbiter | ZX-Spectrum 16K | English |
| 18417 | Orbitter | ZX-Spectrum 16K | English |
| 13293 | Orchard | ZX-Spectrum 16K | English |
| 18213 | Organocomp | ZX-Spectrum 16K | Spanish |
| 10018 | Orpheus | ZX-Spectrum 16K | English |
| 10019 | Orpheus in the Underworld | ZX-Spectrum 16K | English |
| 26726 | Orthius | ZX-Spectrum 16K | English |
| 28156 | Ossuary | ZX-Spectrum 16K | English |