Endless Zombie Rampage 2 is a sweet flash game that pits you as a survivor in a small outpost, against a horde of steadily strengthening undead.
Everyday you must choose what you're going to do- either try and rack a certain amount of zombie kills, find and bring back supplies, or search for other survivors.
Finishing missions and cracking skulls earns you experience points, which you can spend on upgrades, some of which you can see below, and on an array of weapons, all with pretty awesome effects and sound.
Endless Zombie Rampage 2 is a pretty good way to waste some time, and gets hard fast enough that at least one repeat play through will probably be in order.
You can find it here.
Want to find other awesome online zombie flash games? Check out my list.