The launcher is checking for an update, then it stared to update itself, and it says 'restarting the launcher'. Then it just flash for 1 ms and can't launch the game, i tried reinstalling it, but reinstall still needs to check for update, and the loop repeats

You probably need to download the latest updater.

Windows: polytoria.com/download?os=Windows
macOS: polytoria.com/download?os=macOS
Linux: polytoria.com/download?os=Linux

its a proof that its going to hack your computer