Or perhaps rather, how do you play without a gamepad, and without playing terribly?
Last Friday, my gamepad broke. So I tried playing the game using a keyboard and mouse. It looks like the default controls are built around using the keyboard to move and the mouse to click on mobs to attack them. I tried playing that way, and it was really awkward. For one thing, it sure felt like a repetitive strain injury waiting to happen.
For another, I was terrible. Well, not dying in tier 1 terrible, but I probably wouldn't have been able to carry an average PUG through tier 2 like that. Forget about going through an entire level without getting hit; I could barely make it through a decently crowded room without taking damage.
So I thought, maybe I simply wasn't as good at the game as I thought I was. Then my replacement gamepad arrived on Wednesday. And suddenly I was just as good as I had remembered being before. Tier 3 with a gamepad is easier for me than tier 2 with keyboard+mouse.
It's not like I'm using a particularly fancy gamepad, either. It's just a Logitech Dual Action that goes for $17 with free shipping on New Egg. (Is that an ad? Consider that the only reason I replaced it is that the previous one broke.)
So back to the original question: how do you play this game well without using a gamepad? Or is the answer, you don't?
I use my arrow keys along with z and x...do pretty well in runs...I have a gamepad which I dont use at all unless I do pvp.