Due to a engine bug, there was a bug in particle collisions making the game crash in some conditions, it was especially visible when exploding zombies.

We've updated the game to a more recent version of Unity that should fix this issue.

Unfortunately, the latest version of Unity with this fix is not compatible with 32 bits versions Linux. So, if you are still using one of those, you'll have to keep using the Legacy version version of the game.

Let us know if the crash is still happening on this bug thread.

Thanks for your support and sorry for the inconvenience.