Ok, I restarted everything again, and this time steam did a little update, and now it seems to work. Not sure what the problem was. Also, I think these Grimrock games are optimized fairly well, because even though the 310m is an old card both this and the original Grimrock run fairly smoothly. I'm using native resolution and medium high settings and things look good enough so far, might even be able to bump something up if I wanted to.
Thanks everyone. Fingers crossed it stays working.