God of War has a memory leak, which would cause me to crash every 30min to 1hr. The deck would completely lock up as the game used every bit of memory available, requiring a hard reset. You can tell if this is the issue by watching your ram+vram use while playing, the deck has 16GB of memory and 1GB of swap by default, so the deck will crash when the memory leak reaches about 17GB of displayed RAM + VRAM.
What worked for me at the time was using Cryoutilities to increase my swap size, which let the deck handle the growing memory demands. I set mine to 16GB, but 4GB or 8GB would probably be ok. Alternatively you can switch to the beta version of SteamOS, which uses ZRAM instead of swap. I haven't tried it, but this should work as well for fixing the crashes.