Before Redesign
When I started working at Big Viking Games their flagship title was Fish World. It was (and still is) a top grossing Facebook casual game based around collecting fish and decorating tanks, but the UI and the user experience were firmly stuck in the early days of desktop flash games. 
Sometime around 2014 we undertook the huge task of completely overhauling the entire game. While still constrained within the limited Facebook games canvas, we were able to maximize the usable game space while increasing the clarity and usability of the surrounding interface.
After Redesign

Too blue for your taste? We offered 10 different interface colours to choose from.

The redesigned Fish World Shop. Easier to navigate, with better item discoverability, powerful search and multi-item purchasing.

Following the success of our slots feature it was decided that we should try adding other casino games. Much like in actual casinos, roulette proved not to be as popular, but it was certainly a fun UX challenge. I developed a very convincing faux 3D wheel that gave and extremely realistic gaming experience.

A daily retention mechanic based on the popular Price Is Right game, Plinko.