ALT isn't too bad if you get used to tapping it with your SPACEBAR thumb...

to me, Skyrim set up a new standard by making Alt be Sprint instead if having Sprint at Shift.

Really, having to hold a key for a while is much more comfortable using the thumb rather than the pinky finger.

The Alt key is in a really awkward position for my thumb, while the Shift key is literally under the natural position of my pinky finger. In fact, the only key I'd really consider comfortable with the thumb is spacebar itself (which happens to be right under the thumb). Any other key won't be easy to press with the thumb without moving the hand itself.

You don't absolutely HAVE to utilize the mouse. If you have the smarts to design an ingenious auto-aiming system combined with an automatic camera, you would be a fool not to. Take a page from the majority of PSP Action RPGs that only use the D-pad for switching between items and weapons. Since PCs use keyboards you could do something like this:

WASD - Movement

J,K,L, and N,M, < - Attacking

Of course, using a mouse is not a problem at all, anyone who uses a PC is okay with using a mouse and the keyboard at the same time, but if you want a control scheme without the mouse, then auto-aiming and an auto-camera are the only two tools I can suggest.

Reminds me how when I don't want to use the mouse I'd map the aiming to the 8,5,4,6 keys from the numpad. Those essentially end up being in exactly the same layout and height as W,S,A,D but for the right hand, and also allow for a very comfortable position. The biggest downside is that laptops usually don't have numpads, so while you should always provide customizable controls, that still undermines its usefulness as a default setting.

Of course the big advantage of using the numpad is that it's less cramped (hands are more spaced apart), it still has quite a large bunch of keys around, and it's easier to position the hand purely by tactile feedback, without having to look at the keyboard.

The Alt key is in a really awkward position for my thumb, while the Shift key is literally under the natural position of my pinky finger. In fact, the only key I'd really consider comfortable with the thumb is spacebar itself (which happens to be right under the thumb). Any other key won't be easy to press with the thumb without moving the hand itself.

I guess it depends on the keyboard you're using. when you're using [a keyboard with longer Ctrl/Win/Alt keys], the Alt key becomes comfortable to press with the thumb if your hand is positioned so it "comes from the outside" (ie. your hand isn't vertically aligned with the keyboard, but slightly rotated outwards)

Just tried it (the Alt key seems to be at about the same placement in this keyboard), it's pretty much impossible to get the Alt key in a comfortable position without WASD becoming uncomfortable, at least in my case (it does indeed render Shift uncomfortable too, though).