I've got a game tentatively titled "Parking Pushers" that I began to prototype in Unity here. It stems from this thread on Reddit. I think it would work really well in the browser and/or on mobile but I am unsure of the exact mechanics that would make it fun to continue playing.
I picture the game as a physics based multiplayer musical chair style game where the player has to fight to get available parking spaces. For instance, let's say you have a parking lot with 4 open spaces; you start with 5 players driving around the parking lot. Cars leave/spots are signaled open and then and everybody has to fight to claim the available spots. The players have to remain with most of their car in the spot for a duration to claim it within the "round". You could have different gameplay powerups like a magnet that pulled somebody away from a space or an oil slick to stop somebody chasing you or a barrier that somebody has to ram before they can ram you giving you an extra second.
The initial finished prototype could just be vs AI (although I'm not sure if that makes it more or less difficult) and a basic setting with free assets like my demo without any abilities or extras etc. I may continue working on it solo, but I am still learning Unity and am just beginning game dev overall. If this project interests you and you have ideas for it/want to collaborate, let me know.