That was awesome! I did a 2 player game as well but I didn't get a chance to implement AI, so I'm glad you did! I had some difficulty with picking the tiles from time to time, and there were times where I'd place a die down and it'd already start coloring when I didn't pick a line yet, but other than that really well done!
If you wanted to expand the idea (which you don't really but just in case), maybe special tiles on the board with different effects when colored or maybe alternative modes where the objective is different but the gameplay is the same (say maybe color the most of a map, but you have a limited area you have to grow by painting and you can block other lines with your own, kinda like a chinese checkers but with dice). Again it doesn't really need anything, just some thoughts if you wanted to expand the concept more.