Prototype is a good game, but if you don't have an HD tv, i don't think you should get it, see to me the game has the Ps2 graphics, and the game is very.......disturbing to me, it has the "no life feeling in it" maybe you should just rent it mate.
As for the other games i do say get:
1- Modern warfar 2
2- Alan wake (i think you will fall in love with it) sreach it in youtube.
3- Mass effect 2 is a very holy game.