Party Parkade is a local couch multiplayer game where players compete against each other to score points by parking as cars. While colliding into your friends and environment, frantically looking for spots, and experiencing power-ups, the game is guaranteed to spark chaotic entertainment in your homes!
Multiplayer Fun: Compete against up to 4 local friends for the ultimate roadside competition, or beat your time trial in solo play (We highly recommend playing with friends!)
Interactive Maps: Explore 3 different maps, from urban to natural, and battle in highly-interactive environments and terrains.
Chaotic Power-Ups: Fuel your battle with 6 different unique power-ups, creating chaos and unpredictability on the road!
Car Customization: Customize your car with personality through different vehicles, colours and patterns, and hat styles.
It seams when installing the Steam Version on MacOS it is in fact only the Windows version that is copied over!?
When trying to start the game Steam complains about a missing executable at "/Users/USERNAME/Library/Application\ Support/Steam/SteamApps/common/Party\ Parkade/PartyParkade.app/Contents/MacOS/Party Parkade", which indeed doesn't exist, the whole "PartyParkade.app" doesn't!!
Could you please share what OS your Mac is running on? We noticed that there’s been an issue with Steam games running on Macs after they’ve upgraded to Big Sur. We’re gonna be submitting a steam support ticket to try and figure out a solution.
In the meantime, you can directly download the Mac version on Itch.
I just replied on a thread we're having on Steam  (it's MacOS Catalina 10.15.7) (sorry, started this one here before I saw your reply over there) and since I in fact bought the game over at Steam, I unfortunately can't try the direct download on Itch.