I’ve never played The Binding of Isaac’s multiplayer, but it’s an incredible game, infinitely replayable, and has full co-op now (as in you each have a full character rather than just “little brother mode”)
I uninstalled whatever version of it was around a few years ago when it spoiled the f1 I was planning on watching later by sending a push notification with the result the moment it finished
It still feels like it should be orders of magnitude less. For example, if each piece of cheese has an ID number that maps to cheese, an ID for what area it’s in, three coordinates for where exactly it is, and maybe a few more variables like how much of it you’ve eaten. Each of those variables is probably only a couple of bytes, so each item is probably only 20B or so, which means that even if you interacted with a million different items and there was no compression going on then that’s still only 20MB of save data.