Ooh great find, that is a rare scenario bug. I hadn't encountered this yet, but the game over screen should be rendered in front of everything to prevent this stuck scenario from happening. I'll fix this in 1.0.5.
Good idea on the increased pressure on arcade mode. with a timer. I have a similar idea I'm building towards for hindrances in arcade mode: make bonus challenges to deal with in some levels/runs. Thanks for playing!