First of all, I love this. Such a classic concept and you just made it so much more interesting.
I feel like the origin of the light cone could be a bit higher tho, so part of the player is visible as well. Right now I mostly die because I hit the side of a spike, because I feel like I'm already past it.
You could also add some items, that give you advantages like a bigger cone, or disadvantages like a blinking cone.
Overall a great game, it fits the concept very well.