Thomas Jentzsch picked up the challenge to create a working Sudoku game for the Atari 2600. Due to heavy limitations this will turn out into beeing very interesting.

Recent status:

Version 0.12

Dramatically improved generation performance (especially by remembering allowed digits for each row, column and block). Now a medium difficulty Sudoku is calculated in 3 to 10 seconds. To reduce average time for really difficult Sudokus, I abandon the solver if it takes too long and restart the generation from scratch. Still those Sudokus often take minutes to generate and I am not sure if and how this impacts the difficulty.

Implementing an intelligent solver turned out to be pretty impossible due to memory restrictions. I am already using ~94 bytes during generation, so there is not much space left.

Also added some eye-candy (useful for debugging too) during generation.

Next steps:
1. Trying to optimize memory consumption (to allow 2.)
2. Further speed improvements
3. Final digit permutation to hide generation orders
4. A better, non-flickering kernel