You could use the VICKY technique! (available here: https://www.youtube.com/watch?v=25TwN2Wu_EI)

VICKY means Value, Interests, Crazy 8s, Keepers, Yes and.

Value: write down what you want to make. platformers or RPG, 2D or 3D, single or multiplayer… etc. (if in a team, then vote on what you want to make!)

Interests: write ideas. like, anything. write absolutely everything related to luck or not for like 5 minutes. (if in a team, take out your favorites, and explain them to others.)

Crazy 8s: Write (8 maximum) concepts down with the ideas you had. (if in a team, with the best ideas you came up with, and then explain them to others why your idea is, for you, the best one.)

Keepers: You have to end up with 3 (maximum) concepts that you wish to explore. (if in a team, each member has 3 votes. you can put a vote on any concept, including yourself. do not vote on the same concept, you don’t have to use all of your votes.)

Yes and: Add ideas to the 3 concepts you ended up with. (if in a team, then talk about your new ideas to the concepts.)

Now, you’ll have something better to work with!