We could detect if the simulation diverged. Then we had to replay deterministicly up to the frame of divergence and then break on various things that cause dive

We could detect if the simulation diverged. Then we had to replay deterministicly up to the frame of divergence and then break on various things that cause divergence. Floating point underflow/overflow, NaN, uninitialized memory access, divide by zero, etc. If my memory serves correct, the physx code referenced uninitialized memory. We had to patch their binary to initialize it.