Medieval ruler simulation game. The closest you can get to playing Game of Thrones without kidnapping George R.R. Martin to be your gamemaster.

Best Civil War game in the past decade, reminds one of Sid Meier's Gettysburg. Not quite as detailed, but offers similar tactical choices.

Underrated gem of a 4x in space game. Each faction has a different type of FTL drive, and randomized tech trees mean amazing replayability.

Build a rocket, watch it blow up, build more and fly your kerbals into space. Or the ground...most often the ground.

Classic old school strategy game. Create units in companies, mixing and matching unit types to get the result you desire.

The Arma series is the only real tactical shooter out there. Huge map, amazing detail, and presents tactical options not present in most FPS games.

If a game can be described as beautiful, then this is it. Civ style gameplay meets fantasy; heros finish quests as your cities grow in geometric bliss.

Good time waster in the style of old school management games. Plus it's just entertaining to watch your prisoners riot in the shower.

Pretty much the closest you can get to playing a tabletop game of Shadowrun by your lonesome. Excellent atmosphere and immersion.