It's simple. You have 3 days to make a game in 3h. The only thing must be in these 3h is the actual developement of the game (coding, visuals, audio) all other thing didn't count (planning, brainstorming, designing level, building and uploading). And you can split these 3h like you want during the 3 days. This jam isn't about crunching all the weekend but help you to be well organized and efficient.