Sorry to hear that, though I'm not that suprised, given how much there's going on in the game at any given time. It's simulating dozens of individual soldiers seeing, moving, thinking, aiming, shooting and all that simultaneously, and given that I've worked on this alone on my free time, I haven't been able to do all the possible optimizations or test on a varied range of different computers. Thank you for your feedback, I'll try to do better with my future games so that I can cater for broader audience :)