Games I've finished

1. DoomDoomhttps://giantbomb.com/wiki/Games/DoomOpens wiki page

2. Doom II: Hell on EarthDoom II: Hell on Earthhttps://giantbomb.com/wiki/Games/Doom_II_Hell_on_EarthOpens wiki page

3. QuakeQuakehttps://giantbomb.com/wiki/Games/QuakeOpens wiki page

4. Quake IIQuake IIhttps://giantbomb.com/wiki/Games/Quake_IIOpens wiki page

5. Deus ExDeus Exhttps://giantbomb.com/wiki/Games/Deus_ExOpens wiki page

6. Command & ConquerCommand & Conquerhttps://giantbomb.com/wiki/Games/Command_And_ConquerOpens wiki page

7. Prisoner of IcePrisoner of Icehttps://giantbomb.com/wiki/Games/Prisoner_of_IceOpens wiki page

8. Wing Commander IV: The Price of FreedomWing Commander IV: The Price of Freedomhttps://giantbomb.com/wiki/Games/Wing_Commander_IV_The_Price_of_FreedomOpens wiki page

It's been at least 10 years, but I think I actually got most of the endings.

9. DescentDescenthttps://giantbomb.com/wiki/Games/DescentOpens wiki page

10. Cold WinterCold Winterhttps://giantbomb.com/wiki/Games/Cold_WinterOpens wiki page