[codebje]

Side effects and non-determinism can break the relationship between action ("command") and event. You'd need to take care with things such as random number generation, to use a PRNG whose call sequence is determined only by the actions, and whose seeding is an action itself.

Side effects caused by action handlers are also something to beware - don't launch the missiles when you're replaying the past.

[DougBTX]

Reminds me of eg: https://gafferongames.com/post/deterministic_lockstep/