Thanks a lot for the detailed feedback, it really helped! The first boss is meant to be a wall you push through, but you're right that failing it was too punishing early on. In the next update, dying at low levels only costs part of the run's loot instead of most of it, the rest bonus wait starts at 30 seconds and grows with your level, and the Head to Exit button pulses before the boss wave so you know you can leave with your loot.