For those that thought that the programing puzzles where too easy I present SpaceChem.
It has no penalties for trying different things, and that's good, because you will fail a lot. It is a much more complex game, especially since the program is entered on the same space that the executes, the tasks are more complex than reaching the goal and the solution has to be stable.
Or if you are looking for something more similar to the existing ones, look in your local bargain bin for "The lost mind of Dr. Brain", while the easy difficulty is arguably easier than the puzzle agent puzzles, the subroutine puzzles is a lot more difficult.