I fully endorse this post ^ it is full of good choices.
Oh and the
Deus Ex and Hitman games are on sale steam. 50% off each, 60% off the series bundles, 66% off the the bundle with everything.
I love these games, Deus Ex has never been beaten and Hitman is a puzzle game disguised as an action game. The first Deus Ex and the Hitman: Blood Money are the best ones.