If you're struggling to come up with an idea, I'll leave some tips from my experience, i.e. what I do, and then you guys can leave your own tips too.

So what I tend to do, is think of anything I can that relates to the theme, and write down about 5 ideas based on it. Then for each idea, I see if I can come up with a playable game idea based on it, and then choose my favourite.

And by think of anything, I mean anything. So it's celebration, your 5 ideas could be; Your birthday, Exam results, End of lockdown, A wedding, Getting a pet. Then for each one, think of a playable game. So a birthday party where you have to find all the pieces of a gift to give to someone.

All the best of luck guys!