| Title | Publisher | Year | Language | Documents |
|---|---|---|---|---|
| Odessy | Brendan Clarke | 1986 | English | Solution |
| October 31st | Finn Rosenløv | 2022 | English | Solution |
| OCI | Tearsoft | 1988 | English | |
| Oceana | Philip Boswell | 1993 | English | Solution |
| Ocean Hunt | Molimerx |
1983 | English | Solution |
| Ocean Dancer | King Software | 1984 | English | Solution, Map |
| Ocean Beach | James Banks | 2019 | English | |
| Occult Connection, The | David Munden | 1993 | English | |
| Obscure Naturalist, The | Peter Hague | 1990 | English | |
| Obscene Quest of Dr. Aardvarkbarf, The | Gary Roggin | 1997 | English | Solution |
| Oasis of Shalimar | Mountain Valley Software |
1982 | English | Solution, Map |
| O-Level Caper, The | Phoenix Software [1] |
1983 | English | |
| O Zone, The | Compass Software |
1986 | English | Solution, Hints |