there are many many many computer wargames based on PanzerBlitz and it's ilk. The old TalonSoft titles (The ACW, Napoleonics, East Front II/West Front/Rising Sun WW2 titles) sand box games like The Operational Art of War, anything by HPS Simulations, the Combat Mission games, then the more serious stuff like TacOps, Decisive Action, AATF etc etc
that's not to mention the stuff like VASSAL/VASL for ASL.
Battlefront.com, Matrixgames (which has re-released and updated the Steel Panther games - MBT and WW2), are just a few of the more modern companies(or used to be - I haven't worked in the COTS milsim area for a while now.)