Is it fun?

After spending several months building the framework of this game, designing several puzzles and trying to balance the difficulty vs. creativity, I would really appreciate some criticism. Is it too easy, too hard? is the concept boring? is it fun to just design small programs in the sandbox? What other ideas can this lead to? Should I continue the development and in which direction?

Obviously, I have some ideas where I would like to take this concepts to. Some are not trivial and would require lots of additional work. Before I invest in some of those directions, I thought it would be a good idea to provide people with access to the early development of the game and gather feedback.