It can be so challenging to complete your game and submit it in a gamejam, I can confirm that because I expertised that since it is the first game jam I joined, but finally I did it, here is my shooter game with multiple endings Bright Darkness for this game jam. The tips are as follows:
- Keep it Simple, so aim for a simple game concept that you can realistically complete in the time remaining.
- Focus on implementing the core gameplay mechanics first, anything else is just secondary
- Make a list of all the "TO DO" things remaining and you want to implement them, and make sure to order them (this helped me a lot to boost up my work)
- Use ONLY things you are already familiar with! that applies on tools, game engines, components, or anything!
- Before thinking about details and asthetics, prototype first, Trust me, this will be very helpful for problem solving early.
- If you are working on a team, make sure that you have consistent communication, and make sure you have a team leader.
- Focus on Key Elements and polish key elements like the main character, main mechanics, and user interface. A well-polished core can make a simple game feel more complete.
I hope this is useful, GOOD LUCK to everyone, and make sure to enjoy it :)