A game where you control KarBOOM-style cute cars (maybe with a Super Mario Galaxy graphics style), drive at high speed and can grind on rails and edges like in Skateboarding games. There can be ramps and halfpipes (thus tricks) as well, maybe even small wings/ boosters like in San Francisco Rush 2049 so you can rotate the car in the air.

The speed could be incredibly fast like in Extreme-G or F-Zero GX and have either 3dimensional twisted maps as in the latter game or be limited to two dimensions (except grinding) as in F-Zero for SNES.

The game could go for a Trackmania style gameplay where you cannot collide with your enemies and drive multiple laps but go from A and B again and again to get the best time (a surprisingly fun way to play), where the latter version is much easier to implement.