Sorry, hella late reply
I was still a really junior dev when I made this game, and the performance bottlenecks quite a bit due to the heavy-handed VFX. I would suggest:
MINIMUM
Windows 7, Intel Core Duo 2.53 Ghz, 4GB RAM, Video Graphics 512MB SDRAM DX10 capable, onboard sound should be fine. Those are the specs of the computer I built it (and it was out-of-date even back then), so it should be just about the minimum.