Hi, i'm new to the forums of PICO-8, and learning how to use the program yet, but i love the huge community here, so i wanted to share some ideas for fan games in case someone is interested:

1) A game based on Sonic, you can also use other games inspire by it like: Spark the Electric Jester, Freedom Planet or Kyle and Lucy: Wonderland, basically a platformer where you must run fast, you can included any original gimmick if you want.
2) A Castlevania-type game like Bloodstained, where you continue forward while dealing with any enemy in your path, or the Zelda-like Mina the Hollower, a game where you explore different places and get items that help you in your quest.
3) One based on Virtua Fighter, having different fighters with different moves, basically with an arcade mode that ends with a final boss.
4) A game similar to Hypnospace Outlaw, a point-and-click game where you explore a world full of different pages, trying to complete objectives as you see an entire community of people sharing their interests and creations.

Well, those are my ideas, if you want to express your opinion, or share your ideas, you can post anything here, but please be kind, no need to be rude here.