It can be played with just a mouse.  I’m not sure about just using keys.  At the very least this game requires 0 dexterity so you can use one hand for both.

Slow paced game, think of it as a very elaborate and beautiful game of chess.  I’d recommend getting a mouse or trackpad will work. Should be able to play no problem. Very excited for you to try the series it’s a very very very underrated game.

They're made to be playable with just the mouse and they're turn-based so there's no hurry.

I broke my arm badly when in high school.  Didn't keep me from playing Heroes using my left hand with the mouse!

Recently I got a discount code from GOG for the whole series, and I'm considering getting it. One of the deciding factors is if I'll be able to play it though. My right wrist got injured, so I can only use my left hand for gaming. I have a one-handed keypad with WASD and arrow keys, but until I figure something out, no mouse/cursor movement. Does the series require the mouse to navigate the different options, or is it playable without? And if so, how many keys do I need to map?  


Edit: or, on the other hand, can they be played with just the mouse? 

Edit 2: yes, it is! Thanks for the responses everyone!

Do these games require the mouse?