3 Suggestions to make this game awesome.
1 - Lower the amount of damage the enemy tanks do and lower the refire rate of the mortars.
2 - Increase the range and damage of the single shot riflemen dudes, and add a third unit that has a rapid fire attack with the range and damage that we have now.
3 - Increase the speed and damage of Dem. Don't make him too awesome or people will use him solely instead of using their base stuff.
Also, you might want to look at re-balancing the amount of minerals it takes to call down troops. In fact, I suggest you remove minerals all together and just add control points and such. The more control points you control, the more units you can call down.
Minerals don't really add much to the game. I mean, you could just call them something else but its still hella cheesy.
OK this game was just total awesomeness. Reminded me of a game called Critical Mass. ~ http://www.windowsgames.co.uk/critical.html
Now, if only someone was able to duplicate that game ... :P
 "Echoes: Operation Stranglehold"){kind=icon}
 "Book of Mages: The Dark Times"){kind=icon}
 "Invadish 5"){kind=icon}
 "SteamBirds"){kind=icon}