do you get any error messages?
also what is your OS and computer specs?
(does ZortchTest still work and load?)
do you see the loading screen come up at all?
is there any difference if you try to use the itch.io app to start?
I restarted my PC and now it runs without problems, didn't need the itch.io app for that.
Aside from that, the expanded levels are really fun and at the same time quite challenging when you play them at the maximum difficulties, and I do now realize how extremely useful the pistol shield is against hordes of enemies shooting at you or to escape tight situations.