The challenge is in those damn sniper levels, but only because the targetting sucks. also the reward isn't worth the price you bought for it. it's a dumb set-up all around.
Alot of you people shouting for upgrades seem to be missing the point of the game: Surviving under a condition of increasing scarcity. So the only upgrades that wouldn't negatively alter this concept would be minor and cosmetic, and therefore, pointless. So quit yer bitchin'.
Doesn't need upgrades, it's fine the way it is. i wouldn't mind seeing extra levels though, depending on gaining in-game badges. or a ten percent chance of eating someone without infecting them would also be nice (body just disappears).
This is a horrible game. no good explanation of what the upgrades do, no point for collecting 100 gifts, no idea how the game is supposed to end (based on height? Length? time wasted?), no clue how to make new upgrades, and for that matter, no idea what half those things in the air are. you know, the ones that don't seem to DO anything? 2/5 for mediocre holiday effort and naked santa.
Good games, needs some shop upgrades for the guns, and a population limit would be nice too. that way it makes the game a little more 'believable' and allows us to field the units from yesterday in the new day's defense.
it's not as though it's 'like' legend of zelda, it IS legend of zelda, complete with the same rainy intro, general storyline (the triforce), and fighting mechanics. next time try to make something a little more inspired than a straight copy.