Would it be ok, if I'd made my own compiler (game engine) and then make a game in it for the jam?

[...]but doesn't include the code composing your framework or engine.

Hi ooohno! It's best to follow your heart on these rules in this situation. If your compiler is just doing typical engine work, it shouldn't be a problem. If it's handling the bulk of your game code, it might not be the best route. There are no prizes for TweetTweetJam, so you definitely won't get disqualified for stretching the rules, so do what works best for you!