| Title | System | Year | |
|---|---|---|---|
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| The Good Old Days | The Fourth Protocol | C64 | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| The Commodore Zone | Fourth Protocol | C64 | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Abandonware Dos | The Fourth Protocol | PC | 1987 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | 4th Protocol, The | Amstrad CPC | 1986 |
| XTC Abandonware | 4th Protocol | PC | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Archive.org | Fourth Protocol, The | ZX Spectrum | 1985 |
| Title | Genre | Company | Year |
|---|---|---|---|
| Protocol | unknown | Firebird | 1987 |
| Alpha Protocol | RPG | Obsidian Entertainment | 2010 |
| Wizardry: The Return of Werdna - The Fourth Scenario | RPG | Sir-Tech | 1987 |