Is it a TPS shooter ? or an adventure game ? I haven't been tracking this game because I think some of you are on top of it.
It's a "third person" shooter, so to speak. It has an isometric view (ala Lara Croft and the Guardian of Light, Diablo, etc). It controls similar to normal twin stick shooters, in that, you have to use your left stick to move, and your right stick to aim. An interesting mechanic is that you run slower while you aim, so if you need a fast evacuation, you have to stop shooting or you'll move too slow to escape the zombies.
There is also an evasive manuver, a "sprint" that will get you out of a bind quickly, as well as knocks over a few zombies, but will drain your stamina meter and requires a recharge before use.
It isn't an arena shooter though. Each level has many different areas, generally split up by check points that are used to restock ammo, upgrade weapons, and change armor. At each checkpoint, your health is refilled, and you are met with a new wave of undead target practice.
There are many types of zombies, some requiring nothing to kill (these are literally losing flesh as they walk, no clothes, just heaps of meat and bone) and some needing more (fat zombies, or strong ones, usually bigger people). Then there are special types, like a really huge zombie that explodes if he gets to close, and also explodes when you kill him. There are two "boss" zombie types, one with huge muscles (looks like a tank from L4D) and another that has two giant pieces of metal on his arms and will slice you in half if he catches you.
Overall, the movement / shooting mechanics combined with the large variety of weapons and upgradability offer a considerable amount of replay value, even for the the guy not looking for online action (because the leaderboards are extremely competitive, like SSHD).
I know I'll personally be playing this for a long while. Plus, the fact that Sony allowed them to include a Platinum Trophy is awesome, because more achievements, for me, is more reason to continue coming back to the game. Also glad to see them carry on the Zombie Genocide achievement / trophy, awesome awareness on their part (though their number was off by one digit, lol).