First of all congratulations on successful entry in the Jam. Because Scope creep is one of the biggest reason why most jam entries fail. While developing games it is often normal to get very excited and keep adding more and more content to the game. Well sometimes it lead to good results as well but mostly it is what sets the developer off once you go deeper that way, as with more mechanics comes more polish, more assets, more content it also influences the story of the game too. So after facing this issue often I have settled down on some rules-
1. Work On a GDD before even starting a game, layout the features that first to come your mind and finalize whichever you like or able to develop.
2. After the GDD is done. Start developing. Make sure to follow a data oriented and event driven system for the game.
3. Once all the decided mechanics are done, immediately shift to the "Polish Phase". Work on UI and Sounds in this phase. Do the Main menu and entire game flow cycle in this phase only. Integrate story, have game success and fail condition. So at this phase you'll have a complete game.
4. Now play the game, write down bottle necks, see if its enjoyable, see what's not working, see what's missing and then only you make a plan to add/modify a mechanic. If it does not work for your game then only you add or modify stuff.
For this Jam this helped me a lot, and finishing the game was quite easy and i could really focus on making the systems i have very polished, reactive to player and enjoyable.
Check out my game to see it in action.