I really liked this. Except for three somewhat serious gripes:
1. The window is WAY too small. I don't know why many developers don't understand this. Especially those targeting browsers. But we're not using 1024 x 768 anymore. I use a 1440p display which is the rational choice. The bulk of people who haven't figured that out yet are using 1080p. And at both of those resolutions this is unpleasant on the eyes. I zoom in to play. I should not have to.
2. Way too slippery. Does not allow for the tight handling that makes a great platformer shine.
3. I'm not sure why you felt the need to have gravity be so high. I'd definitely tweak that.
I liked the minimalist approach. The audio fit but there should have been a little more to the ambiance. Some subtle parallax or particle details. Jumping (color shifting) sound. Landing sound.
The art was good too. It made me nostalgic about the days of games like ZZT and MZX that utilized ASCII characters to surprisingly deep effect.