Definitely has the be the newer Hitman games. I’ve only played the first two, but I hear the trilogy is an amazing package that would give you potentially hundreds of hours of playtime. They are really incredible sandbox games with tons of replayability. Other than that, Aragami 1 and 2 are fantastic too. They remind of of the old Tenchu games on PS2.
In Shooters you have the Far Cry series, Ghost Recon Wildlands, Metal Gear Solid 5, Sniper Elite 4, Sniper Ghost Warrior 3.
Others from my notes—haven't played many of these:
Assassins Creed Series
Batman Arkham City
Chronicles of Riddick
Deus Ex Mankind Divided & Human Revolution
Horizon Zero Dawn
Mark of the Ninja
Sekiro Shadows Die Twice
Splinter Cell Chaos Theory
Thief 2 The Metal Age