1) Europa Universalis IV - 4.9k Hours
2) Stellaris - 1.4k Hours
3) Crusader Kings III - 1.3k Hours
4) Crusader Kings II - 1.1k Hours
5) The Elder Scrolls V: Skyrim - 709 Hours
6) Mass Effect Trilogy (Original and Remaster, not including 3 on Origin) - 601 Hours
7) Cities: Skylines - 536 Hours
8) Sid Meier's Civilisation V - 493 Hours
9) The Elder Scrolls III: Morrowind - 457 Hours
10) The Elder Scrolls Online - 194 Hours
11) Hearts of Iron IV - 142 Hours
12) Besiege - 119 Hours
13) Assassin's Creed Odyssey - 102 Hours
14) The Elder Scrolls IV: Oblivion - 92 Hours
15) XCOM 2 - 87 Hours
16) Victoria II - 87 Hours
17) Saint's Row IV - 75 Hours
18) Half Life (including Black Mesa) - 73 Hours
19) Kerbal Space Program - 72 Hours
20) Spore (including expansions) - 72 Hours
21) Half Life 2 - 68 Hours (including Update)
22) Robocraft - 65 Hours
23) XCOM: Enemy Within - 59 Hours
24) Sid Meier's Civilisation VI - 58 Hours
25) Starbound - 56 Hours

As of July 2024