| Title | Publisher | Year | Language | Documents |
|---|---|---|---|---|
| Ogres | Alan DeNiro | 2003 | English | |
| Oily Deeps, The | John Cater | 1999 | English | Solution, Map |
| Old Sherwood Cemetary, The | Duchess | 2002 | English | Solution, Map |
| One About the Chicken, the Lion and the Monkey?, The | Sam Barlow | 1998 | English | |
| One Night in the North Atlantic | Christopher Huang | 1999 | English | Solution, Map |
| OnNoEf | Evin Robertson | 1999 | English | Solution, Map |
| Orpington | William J. Shlaer | 1998 | English | |
| Oth. | Gunther Schmidl | 2002 | English | Solution, Map |