Ever had an initial idea planned out, but after you implemented it and tested the initial gameplay, it is not as fun as you thought?

I've done some testing of the puzzle element of my current project, and it did not meet my expectations.

I'm currently re-writing my gameplay code, thinking of a way to make it more fun. It plays like a standard horizontal scroller; there will be 2 relatively short phases, each with a different gameplay element added to it.

Here is another screenshot of what I have so far: