An open source, smash style fighting game, it could use mascots from foss projects (just like SuperTuxKart do).
Since there are some SSB knockoffs being released (All-Star, MultiVersus), why not make one that is actually good? I think it would be pretty cool :)
Oh yes please do! A lot of people would like to contribute i believe :)
Also worth noting: that’s typically the kind of games where subtle physics settings change the gameplay a lot. It’s worth working on a customizable engine as a library (where you can set settings and import characters/maps) rather than a specific gameplay people may enjoy or not.