When we invented the concept of ON/OFF, it was impossible for us to know whether the game will be easy or hard. The different kinds of blocks came to us naturally, without looking for them, and instantly formed a consistent whole. It was therefore obvious that we had to develop this idea.
A few hours later, we had a working prototype, then an iOS native network-based puzzle editor that allowed collaborative work. This editor helped us to experiment all our level design ideas. This simple concept would eventually lead to a lot of puzzle ideas. We spent entire days and nights working with this editor.
By dint of practice, we acquired a perfect mastery of the concept and its resolution methods. ON/OFF is "algorithmic": to solve a puzzle, one player needs to design a specific algorithm (consciously or not). It often requires to think several moves ahead. Some players admitted that they use a sheet of paper to solve the hard ones.
During the early development steps, we had only a concept in mind and no idea of the set of possibilities. During the advanced steps, we had acquired so much skills that every puzzle seemed solvable by everyone with a few efforts.
We wanted to release the game before Christmas. In order to be ready in time, we neglected a key development step: make real users play ON/OFF. We did it too late. The game was already submitted and ready to be launched. Observing "real" people playing ON/OFF made us understand that it was probably too hard. After the release, there was no doubt anymore: too much players were quickly discouraged and leaved the game before the end of the 40 free levels.
This problem triggered a very bad profitability. We expected that 5% of the downloads would lead to an in-app purchase. We barely got to 1.4%!
What should we did? It was out of the question to discard our beautiful hard puzzles. We put too much efforts into them. It was also out of the question to fill the game with easy levels because this concept shows appeal only if the puzzles are hard enough. We released an update allowing to solve the levels in any order, but it came after the download peak and had a limited effect. The satisfaction of the 150 NASA engineers who completed ON/OFF
Without knowing it, we created a game for NASA engineers. It isn't exactly what people look for on iOS. As software engineers, we hadn't been able to put ourselves on the same "level" as the average users who want to entertain themselves rather than to solve math problems.
Well, we have no choice but to assume the fact that ON/OFF is hard. After all it could be a benefit, a clear way to differentiate our game from the others. ON/OFF is probably one of the most difficult puzzle games in the App Store. It would fit more easily on a dedicated console (Wii U...) though.