You don't even get kernel panic, the machine just freezes.

Just to confirm that, add the following to the kernel line options in grub
"panic=30" . Then freeze the computer again.
If the kernel panics, then it should reboot after 30 seconds.

Do you have a temperature reading for the Mother Board chipset? Can you make
sure it doesn't overheat or something during gameplay?

Use ssh to log into your computer and run `watch sensors`. You will have the
last readings when the computer hangs.

I think you should try to compile a vanilla kernel and enable every debug
option that you can. (You can use the SUSE kernel /proc/config.gz as template).