We've been doing apps and puzzle games a lot on this feature lately, so let's not forget what makes a game really fun: a big robot blowing up lots of stuff. Fortunately, Battle for Cydonia
is full of that, as you control a mech armed with dual machine guns through a series of missions on the future planet of Cydonia. It's a pretty simple affair, but the multitouch controls really make it shine -- you draw a path for your mech to take, and then just tap on enemies as they appear to shoot them down. You can upgrade the mech and its weapons over time, but the core gameplay here is just opening up a can of hot lead on anything that crosses your path.
And plus, it's a free download right now -- if you like the game, you can pick up a "Signal from Titan" mission pack with new weapons, levels, and enemies to face off with for just 99 cents. Battle for Cydonia
is an excellent little sci-fi shooter that's definitely worth the price.