| System (Setting) | Publications | Articles |
|---|---|---|
 Tales of the Valiant | 1 | 1 |
 Talisman | 1 | 1 |
 Teachers and Tentacles | 1 | 1 |
| Techlandia | 1 | 1 |
| Teen Detective | 1 | 1 |
| TekHL | 1 | 0 |
| Terror in the Theatre | 1 | 1 |
| Terror Paths | 1 | 1 |
| Theomachy | 1 | 1 |
| Thrilling Adventures! | 1 | 1 |
| Tides of Madness | 1 | 1 |
| Tindalos | 1 | 1 |
| Tiny Cthulhu | 12 | 24 |
| Tiny Epic Cthulhu | 4 | 4 |
| Titas of Arkham | 1 | 0 |
| Tomes of Arkham | 1 | 1 |
| Touched By Evil | 1 | 1 |
| Tower of Madness | 3 | 3 |
| Towers of Am'harb | 1 | 1 |
| Trail of Cthulhu | 162 | 392 |
| Travel Guide | 2 | 2 |
| Travel-Sized RPG | 1 | 1 |
| Traveller (Chthonian Stars) | 2 | 20 |
| tremulus | 14 | 21 |
| True 20 | 1 | 9 |
| Tunnels and Trolls | 6 | 7 |
| Two Rooms and a Boom | 1 | 1 |