I am working on a multiplayer mode (it will take a while), but currently I am making an FPS for the UE4 Spring Jam. It will have splitscreen and (hopefully) online play. This should be out in the next few days.
What steps did you take to fix it? I have other users reporting those same issues. Also, I am working on 2 new maps for the game, which means the mac version will be updated to the latest version once that update releases (ETA: 1-2 weeks).
Nothing too complicated, I just downloaded the itch.io Application and downloaded Project Tetra from there. After it downloaded, I just clicked ‘Run’ and it worked!