One of the things I found interesting about the game was its scoring system. The scoring system works like this: for every tile 3 * 2^n, you are awarded 3^n points. It's sort of the equivalent of writing your number in (broken) base 2, and then reinterpreting it as base 3. Gameplay wise, this system guarantees that combining two tiles will yield a score that is greater than the original.
This had me thinking about another base system: the Fibonacci base system, which is explained more thoroughly than you could ever ask for here. The Fibonacci base system represents numbers not as sums of powers of the base, but instead as sums of Fibonacci numbers.
Well, I had the idea: why not play Threes, except that instead of "overflowing" base 2 representation, you overflow the Fibonacci representation by combining two adjacent Fibonacci numbers?
So I went and coded the game. My javascript skills are not so great, so the game's just a terminal game for now. You can download and run the game with python fibs.py
http://moderndescartes.com/essays/fibs