Keys very nearly placed among the winners in our first game design competition (CGDC #1), and if we had but one additional prize, it would have. This mysterious and charming little puzzle game fit the theme perfectly by closely resembling a puzzle you might find in Click Drag Type. In fact, there weren't many other games that came this close to exactly what we were looking for.
Rob Allen of England, UK, is the creative force behind this delightful game of sight and sound. And if you're concerned about accessibility, don't be alarmed: the game can be solved with the sound completely turned off. But keep it on if you can, as it adds to the overall enjoyment of the puzzle.
It is a simple puzzle that will surely have you scratching your head with wonderment while trying to figure out exactly what to do. But it's not very difficult, so I don't want to give away anything about it here.
Analysis: If I could make one change, it would be the implementation of a more complex set of rules governing each 'key'. As it is, once I figured out the key it then became a simple task of trial and error. Overall, Keys is an excellent puzzle that leaves you wanting more.