Hello, I wanted to ask if the game has to be in a 3D format. I am a beginner developer and I'm still not very skilled at 3D modeling, which makes it very difficult for me to create assets. (I also don't like using free or paid assets.

No limitations except try and pick one of the themes, but if you can't that is okay to just try your best and get something done by the deadline. There is no limitations really. Even if you didn't follow the rules I don't care, but that is just what it is being judged on. All I care is that you learn something new and get a little bit better at making games.