A prototype is the bare bones version of your game. Try to get the basic game loop you want and see if its fun then build your game around that basic game loop.
Just start off by deciding what kind of game you want to do and make it easy then just copy and paste someone else's code that is if you do not want to have the fun of making code
Check out brackeys on YouTube its very useful... Also if it allowed in this Jam use assets they are so helpful... For instance Im bad at doing effects so I use assests/plug in that makes it simple... Also u can checkout other games on this site and take ideas and then add ur own touch and tweeks.
