You didn't specify what kind of games do you like so I will just list mine:
Strategy games:
Europa Universalis 4
Hearts of Iron 4
Stellaris
Victoria II
Cities skylines
(All of them with all DLCs)
Wargame: Red Dragon
911 / 112 operator
Total war series
Natural Selection 2 (Hybrid FPS + Strategy game)
Workers and Resources: Soviet republic
Totally accurate battlesimulator
Xcom 2
Emergency 2017
Men of war: assault squad 2
Prison architect
Civilization series
Games you could play with your friends for a long time:
Divinity Original Sins 2
Life is Feudal
SQUAD (Is really cool if you play alone aswell)
Holdfast: Nations at war (same as above)
Some games I personally love. Some of them are more FPS or a bit older:
Foxhole
Elite Dangerous
Star citizen
Arma 3 (Without DLCs or Mods, it's shit)
Hidden and dangerous 2
SWAT 4
Escape from Tarkov
Gothic (1 and 2 are gold, 3 is wonky and never played 4) or Risen but they are... Idk... Not good old gothic
Any GTA game
L.A. Noire
Witcher (Any game)
Mafia series
Vietcong series
For Honor
Or if you want some free gamez cus you're poor student like myself:
Warthunder
Planetside 2