I doesn't run on Mac OS Catalina
Viewing post in Digital Logic Sim (old version) comments
Could you try downloading again please, I've made a change that'll hopefully help. You'll need to open it by right clicking > Open (not double-clicking) then it should give a warning, but allow you to open anyway. Alternatively, if you download it via the itch.io app (https://itch.io/app) it'll work fine.