To make more complete criticism, and obviously I don't want to sound harsh or anything : 

- The base idea is interesting and could be expanded upon with a cool mechanic forcing you to retreat to the shadows and pick the right time to turn the lights off (maybe with enemies) ? But I think it also works as is, except for the respawning crumbs (they do take away at the main idea because you can just stay at the same place and spam on / off).

- I think the main thing you should focus on now is gamefeel and graphics. For example, because the character has no acceleration, it feels bland to move around. Similarly, nothing really happens when you collect crumbs, it would've been fun if there was a bit of freeze and screenshake for example (note : I only make action games so I might be biased towards screenshake), which could be easy to implement. Overall, I'd suggest looking into gamefeel theory and how to make simple things feel better.