This was pretty fun to play as a rage game. Some mechanics weren't explained, but these were all simple enough to just stumble across them. (Wall jumps, wall climbing and how to defeat the boss)
I struggled a lot on the wide jump with spikes above the player character's head, but that's basically the only point I'd consider unfair.
I didn't expect the twist after the bossfight, but I guess it makes sense. You defeat the program's executioner, but the program just tells you to restart so it can send another.
This is a very well rounded game (not only story wise :D)