Unity of Command is a very enjoyable East Front computer wargame. It is on sale this weekend for $5.99. Very much worth it at that price. It has multiplayer player but to it it is best suited for solo play against its devious AI.
It has DLC available also on deep discount.
Check it out . . .http://bit.ly/U_of_C
You can also get extra copies for friends on the same order for 1/2 off (again)... so it drops to $2.49 and $3.49 each.