Really neat concept. I liked having the rulebook as part of the game and being able to mess with the rules yourself. Tic Tac Toe worked really well for that and was fun to figure out.
Rummy was where I had to admit defeat though. I have somehow made it this far in life without ever learning how to play it, so trying to learn Rummy and keep track of changing rules at the same time was a bit much for me. Still, a clever use of the theme and fun to try out.