Two of my favorites right here:
Cortex Command:
http://www.datarealms.com/Your a disembodied brain controlling clones and robots on a planet. Mine gold and then buy weapons and more soldiers to kill your enemies! A fun physics engine and destructible terrain. I've known it for a long time and its paid back the money that I bought it for.
King Arthur's Gold:
http://kag2d.com/I found this game out in the Cortex Command forum actually. Its another 2d scrolling game. While the above game is hotseat, this game is online multiplayer. Focuses on team work, since the individual classes in the game can't really win by themselves. If there was another game you could compare this too, its like Terreria. Build fortesses and then try and crush the other team's fortress.
