Age of Mythology is the best way ever to have continued the AoE line. But this time there are Gods and Titans... TITANS!!! TITANS KILLING EVERYTHING!!

Original AoE 2 is super old and super fun, but the HD version is even better. Brings back memories. One of the best RTS style games on the market.

A really old game, but still a great one. Best part is the space battles, where you shoot down small ships and destroy mother ships. Pretty cheap too.

Pretty fun MOBA, hard to get used too, but once you do, its pretty dang fun to gank noobs.

CastleCrashers is an amazing sidescroller hack and slash games, the story is funny and the end is a hilarious plot twist. Poop jokes all throughout also

BattleBlock Theater is one of the most fun yet frustrating platformer games ever. But is totall worth all the raging. Plus you can change your head-face

All the Half-Life games are amazing fps singleplayer games. The story is so great, and the action gets intense. Now if they would just make Half-Life 3.

Garry's mod is a great sandbox game, excellent for playing with friends, and many gamemodes to chose from. The addons/mods add countless hours of fun.

Its not even a complete game, but its already more complete than most newer games. Its an amazing sandbox/puzzle game with hundreds of possibilities.