[OkayPhysicist]

My go-to for pen-and-paper style puzzles (including Sudoku, but mainly Loopy) is Simon Tatham's Portable Puzzle Collection [0]. It's extremely portable open source C, so if you can compute on it, you can probably compile STPPC for it.

[0] https://www.chiark.greenend.org.uk/~sgtatham/puzzles/

[emmelaich]

There's a nice html5 web version here: http://medmunds.github.io/puzzles/

The sudoku game is called solo.

*in addition to the js versions on the original site.