Oddly enough, I like the barebones simplicity of this game.
WASD controls - Good
Instant restart upon death -Good
Platforms colour coded - Good
Sadly the second level reverts to arrowkey controls only. And there are no levels beyond the second.
The first level, has a in the top left corner, and this bar seem to appear on screen when the level resets after death. The text on the first level is hard to read due to poor placement, sizing and font choice . I would suggest a font like "FFF Forward" which is free to use, easy to find and fits your current theme. Then placing text where it is not obscured by platforms, and at a large enough size so that it can be seen casually (note that this includes making the text stationary, rather than having it follow the player).
Right now, I might want a replay button, but when you have more levels, you may want to add a menu/ a level select screen instead.
I like what you're doing, you have potential, keep up the good work.