A warning would have been nice but I guess for $5 I can't complain that much.
List of games that won't run on MacOS Catalina:
Nuclear Throne
Super Rad Ray Gun
Master Spy
If you find any others post them here.
Try using
https://docs.google.com/spreadsheets/d/1cbOqO6rq0YYWPKmci8Pgv4YGWcl4NQUX9EAj221Ze30/htmlview?pru=AAABctTN-DU*49kK-jQ6yvmWG3mH_0zQ1w#gid=782418878
I dont know if some Macs are different but it should make it easier to tell if it's mac supported or not.