Nice and cool game, simple as of yet, but a fun idea. I think if you developed this further and added others features it would definitely be a fun game to come back to.

cool

I don't know.
I like the art style and colour palette, the idea of travelling through a dark cave…
But after a while, the constant flashes started to annoy me (it's hard to watch), and when the giant flying block killed me I lost interest because I'd have to go through the entire game again (and possibly many more times).

For the latter, consider adding checkpoints. Please. E.g. a torch you can ignite.

For the former… I'd recommend you to look at the gameplay of 'Candleman', it's a game with a similar idea about a platformer with limited light. You might find it useful as a source of inspiration (even though it's 3D).
https://youtu.be/HpIihc3devs
Key thing:
– You're never in a *complete* darkness, just bad visibility. So you're not necessarily forced to turn on the light just to move around. (your previous path is even marked by molten wax)
Only when you need to be precise in avoiding gaps or see further.

I think it'd work for your game as well – make the lighter limited (perhaps add a collectable refill), but make your close surroundings visible even in the dark (e.g. dark grey). A simple way to limit to "close surroundings" might be with a black png image mask with a transparent hole in the middle enabled/disabled in the foreground.
And to make it easier to watch, I'd try to make the dark→light transition gradual, instead of just flashy on/off.