Color Commander is an interesting new style of game derived from the old “defend your castle” games. You purchase monsters to run across the screen eating developing castles. You are rewarded money for every castle you chomp down usable to purchase new monsters and monster types.

I think the game would be better without a time limit and if the castles were built in lanes. Then instead of releasing individual monsters you would release waves of monsters and be rewarded for being about to destroy castles in the least number of waves with the cheapest group of monsters. A hero system would also be interesting if the hero only survives if that wave gets through.