is it important that our game match with the theme

I think it does...if you don't have a Idea at least making something is always great 😊

If you want to win then it must adhere with Bada Soch or Think Big. If you here just for fun and want to get feedback from other game devs it is okay if your game does not follow the theme. Either way I don't think they will disqualify game if they are not following the theme. So don't worry. Create what you love!