Is there a limit to how long a playthrough of a game takes? For example, would you "disqualify" a game for taking an hour or more to complete on average?

Hey! No, we wouldn't disqualify it! The game can be however long you'd like. I think most Adventure Jam entries have been anywhere between 10-60 minutes long. There could be a possibility that community members won't have time to finish your game during the voting period if it's longer than that depending on how many games are submitted, but we won't stop you if you think you can pull it off and produce it in a healthy way (getting enough sleep, food, not burning out, et cetera). I hope this helps! :)