Ditch the installer, super annoying now that I have to uninstall, try just doing the exe or zip. The game is good for 5 hours but tedious to play, can't see any reason for spikes and holes as they serve the same purpose.
Even though it's just cubes, the graphics make it easy to tell what's want (spikes, pits, etc). I like the idea of only being able to jump in one direction. Would be interesting to take that a step further and have it be physics based on the momentum you have when you jump and that once you've jumped you have no more control over your trajectory. Fun little game.
The "Web" and "Windows" link both point to a download for a Windows exe, so you should consolidate them into one link that says "Windows".
The points counter is pretty pointless (pun intended), since it both resets in the middle of the game after losing a level, and also carries over between playthroughs (so you can rack up points by playing the first level over and over again). Also, the audio plays over itself every time you restart, which is hilarious, but also really loud after several resets.
Other than that, it's a fairly well-made platformer, with nice minimalistic graphics. A good entry for just 5 hours!
Not bad for a 5 hours of development, and it addresses the "two button controls" theme, too. I'd have liked some other controls, e.g. right for going right and up for jumping. The collisions seemed to act weird sometimes, too (especially when I was killed by these mean spikes :< ). Also, where you got the soundtrack from? I believe I heard it somewhere before...
Even some basic audio could spice it up a bit, but otherwise it's a simple platformer.