Making replays that can play back actions on in-game monitor screens

This has been quite a technical challenge, but I've finally got something presentable. There will be a special scene in Fist of the Forgotten that replays events of the game for... reasons, which means I have to store enough information in the save file to keep track of player and enemy positions, velocities, inputs, states, etc in an optimal way so they can be retrieved and recreate the scene later (without impacting the playable scene!). Also have some threaded loading to seamlessly load the levels displayed on the monitors in the background without hitches.