The concept is cool and i liked the boss's design :) I think the fact that the boss emits red light cheat a bit the game since i never used the control input, I only pressed space when i saw red, maybe you need to recompute timing.
Some ways to improve from the top of my head:
- The camera work could be more dynamic. Give it more impulse, you're trying to sneak behind your boss dammit! So strong start + a bit of camera shake to show that you are in a hurry.
- Events that may trip you up or alert the boss. It becomes a bit redundant past de 6 hours (by the way, I won before attaining 12h, dunno if it's a bug)
- Sound design, I know it's difficult being a solo but sounds help a lot to communicate feeling (speed feeling or meaness of the boss for example)
voilà!