Great concept. At first it was hard to get the correct colour. But you get used to the J,K,L keys quickly. One thing I noticed is if I choose the wrong colour and try to re-choose in mid jump the colour shceme has already changed meaning there is no room for second chances, this meant dying a lot, having to click the mouse each time you die is anoying, it would be better to have a button like space bar to retry. What was that thing chasing you on later levels? It never caught up to me (I assume I'm supposed to out run it?).
The difficulty increases at a nice rate with disappearing platforms, nice simple game.