Zombie games are dime-a-dozen nowadays, but their quality varies greatly. One recent game that stands out from the crowd is Decision, a top-down shooter that really got the apocalyptic survival mood down. A variety of upgradable weapons, abilities and unlockable achievements complete the experience.
A screenshot is attached, and below is a video of me finishing the last level and the final boss:
http://www.youtube.com/watch?v=_hX1IvcON1YPlay the game here:
http://armorgames.com/play/12983/decision