what is paTD3: this game is a sequel to the first two games, a Tower Defense game, with funny graphics and (as the name already says) you have to kill penguins. to do that you build towers and eventually go lvl up. with each level you can choose an upgrade, new tower, more cash at start or choose upgrade for your tower.
pros: funny graphics, good combination of towers, nice level up, multiple levels, variety of penguins.
cons: it is not really an improvement from the last two.
difficulty: i would say that if you play it for a while you will get the hang of it, that is if you play seriously. i think that it is not a very difficult strategy game, so difficulty i'd say a mere 5/10.
So with al of this i'd say a 9/10 (do give your opinion and why)