Got up to 311 seconds. :)
This style of horror game isn't usually a genre I prefer, so the low stakes for this game was actually nice for me. It felt chill and tense at the same time. I also found it interesting that the entity's sound was mechanical. Made me wonder what it was I was running from.
I think what the game lacks most is variety of gameplay. Once I figured out that the room was an enclosed grid, I was able to consistently keep away from the entity by skirting the outside of the box. The game needs to find ways to force me away from doing the optimal path, or a more varied geometry that is harder to cheese.
Overall, though, great job! I enjoyed this more than I expected to.