Allied Star Police is a fun little game with a touching backstory: developer PopCap Games helped create this simple, side-scrolling castle-defense-style game through the Make-a-Wish Foundation, for a 9-year-old with leukemia whose wish was to make a video game.
Befitting a game co-created by a 9-year-old, Allied Star Police is action-packed, quick to play, and not too complicated--with cool graphics and animation (even cooler on the iPad) and a loud, rock-out soundtrack. The game pits you (the Allied Star Police, of course) against the evil Flamions, as you send competing waves of well-armed vehicles toward each other's bases.
Your base is on the left end of a long 2D battlefield, with the Flamions' base on the far right, and combat occurs in four horizontal lanes between the two bases. You tap the vehicle you want to build with buttons along the bottom of the screen, and then tap the lane you want it to roll into from your base--from nimble, fast-to-build ATVs and Snipers up to bigger Tanks and the hulking WCSV. The deadlier the vehicle, the more it costs to build and the longer the cooldown before you can build another. You earn money by destroying Flamions, and each game is a steady arms race until you can build up enough momentum to reach and destroy the Flamion base. You can also tap other offensive options, such as bombs, an orbital laser, and a temporary power-up boost for one vehicle.
For a game that's so slight, Allied Star Police shows off PopCap's expertise in its well-done details, from the radar and number cues for each lane (so you can better plan your advances) to the small strategic choices that'll have you thinking on your feet as you replay the game's three difficulty levels to try and beat your best time (like, for example, hiding your powerful but fragile snipers behind your beefier units, or making optimal use of the temporary turbo and bombs). Young kids can play--and beat!--the game's novice setting, but even experienced players will have fun tackling the "insanified" setting. Allied Star Police may not have a ton of depth, but it's a fun, free download for fans of fast-paced, pick-up-and-play shooters.