gjroper: I can play the game for about 10-15 minutes then it heats up the ati radeon hd 4800 series graphics card to the point of shutting down the system similar to what happened to me in Diablo 3, in D3 the solution was to reduce framerate to below 30, is there any fix for this or any program that can be used to reduce frame rate while the game is running? any help appreciated.
short answer: That's an well known behaviour: enable vsync (60fps) or set the frame rate limiter to around 40fps in the cfg (see here:
http://www.grimrock.net/forum/viewtopic.php?f=3&t=284&start=40#p27241)
long answer: grimrock is only GPU limited (not CPU) therefore GPU's running always 100% and can potentially overheat. You can see LoG as GPU stability test, so it seems your systems has not enough cooling reserves.
PS: if you don't achieve 60fps (vsync) or 40fps (limiter) with your card, you have to lower the limiter value further... or reduce resolution (windowed mode allows <1024 resolutions) or clock your GPU down to frequencies which can be cooled (with e.g. ati tray tools)
PPS: with last patch (1.3.7) there was a additional option setting introduced for weak cards, preventing this behaviour (so you can save your money for an GPU update)
