This game has potential. The gameplay is a little more frustrating than it should be, because the "falling off cliffs" aspect isn't really a thing; it's styled like a 2D side-scroller but the controls and movement are top-down style, and this is a bit awkward to get used to. I think that might have just been a limitation of the engine you used, which is fair; it's still very playable, and once I got used to it, it was a decently fun puzzle game.
It looks nice, though very simplistic, and more variation could certainly be introduced in the environments and textures. I have similar things to say about the audio; the ambient music is great for the underground caving feel, and I wouldn't change it a bit, but I would like to hear some variation in sound effects, even just when shooting flares or something.
The "Lightshow" theme was implemented perfectly well; no issues there at all. The "Only One" limitation is only okay to me here because indeed, there is only one exit, and not just only one life; that is significant to the gameplay as a limitation.
The 3 flare limitation could be more interesting if the flares actually shoot and hang in the air or stick to a wall, only illuminating part of the cave and then burning out after a certain amount of time. The whole game could be expanded with different kinds of environments and maybe even different amounts of flares and different light sources you can use in different stages. The overall concept is great, and I would definitely play a game like this again if it featured more elements like that (and if the movement was truly side-scrolling, with the player character walking on the ground).