Making the only controls be the arrow keys is one thing, but making a combat system out of it is a whole 'nother level of impressive. I like how killing enough spiders will eventually cause the "battle difficulty" to increase (i.e. more arrows to press), meaning that it's very easy for the difficulty to spiral out of control if the player is too lax while exploring the game map (since they'll keep killing spiders as they appear). Once you're aware of that however, there's this sense of nervous tension that "something" is going to jump out from the forest once enough spiders have been killed, but (like some of the other commenters have stated) I wasn't able to reach far enough to see if there was anything at the very end.
There's mention of an "exciting boss fight and reveal a plot-twisting ending", but it would be nice if there was a way to save progress (even just checkpoint flags or key items collected) because the alternative is restarting all progress from the very beginning, which can be frustrating once battles start consisting of 5 arrows (the point I reached in the game, and I didn't know if there would still be more arrows to come).
The art and atmosphere are both great however, and I would definitely want to see more of the game's story and (expanded) gameplay.