I wanted to play this once I found it on Steam, but the screenshots didn't seem like the game was worth the $3 price tag...and it isn't, but during the Steam Summer Sale, it got marked down to $0.75, so I had to pick it up. I wasn't expecting to put as many hours into it as I have since most of the people that reviewed it didn't even play the game for more than an hour, but it has some pretty cool features. There's a variation of weapons from pistols, shotguns, bolt rifles, grenades, fireworks to distract your enemies and so on, about 10-15 different zombies, an upgrade system for your character, and a few game modes.
Dead Pixels is basically a wave based campaign mode that gets harder and longer as you raise the difficulty and ends once you reach the extraction point. The Solution gives you the choice of a few characters to choose from with already upgraded attributes and your goal is to make it to the nuclear facility to trigger an explosion that will wipe out the city. This mode was my favorite because you have to make it all the way there, without traders to buy goods from, (you get ammo and guns from looting and calling in drop boxes from your commander), and then run back before the nuclear reactor explodes. It sounds annoying, but it's the best mode in my opinion. And survival. Would it really be a zombie game without survival?
I only have a few problems with this game. The hardest difficulty mode is ridiculous. It should be called impossible mode. Yes, you can beat it, but when you switch from hard mode to hardest mode, you rarely get any weapons or ammo and traders really only appear at the beginning of the game and at the end. May as well just get rid of the traders and force the player to bash his way through. Hardest difficulty isn't bad because it's hard, it's bad because it's extremely cheap and significantly unbalanced. My other complaint is really a recommendation. Just add bosses and it will vary the feeling of the game instead of running constantly down streets shooting the same zombies. Also, the achievements seem buggy, so you could be looking at a few extra hours just to find ways of unlocking them, even when you already did what they said.
If you see this game on sale and you like zombies, pick it up. Otherwise, wait for Dead Pixels 2 or just let the game be.