Awesome game! I hardly ever go for indie titles or casual games, but this one is a total anomaly! With damn near infinite replay value thanks to the fly/time/ladybug challenges plus a global leaderboard, this game has had me hooked since I picked it up 24 hours ago.
Spy Chameleon has one of the best learning curves I've ever experienced in a game - many levels are made in a way that is easy enough to complete, but difficult to master, especially in the later stages. The difficulty very gradually goes up, to the point where you don't even really realize that it's getting more difficult until you're trying to break the world record and you fail 50 times.
The mechanics of the game aren't introduces all in the first 5 or 10 stages, which I believe is an extremely strong point. It gradually introduces new mechanics over each mission of 15 levels, so you aren't bombarded with new gimmicks but learn exactly how each new obstacle works and can be overcome.
Spy Chameleon is one of the best games I've played in quite a while. It stand out in my mind for being so different, while pretty much nailing the difficulty curve and keeping the player interested. I've started a subreddit, /r/spychameleon, in case anybody wants to check it out or if the developers want to take over as moderators. But yes, I very much do recommend this game to everybody, so worth the price!