A simple snake game with javascript, you can start playing here
you can choose a level first with the level select, and the block size too, and then hit the start button to start the game
I still have a problem in the performance, while it's playing it might lag a little bit, here is a link to my question on stackoverflow to have more details.
you can add your cusrom maps to the game, refer to how was the third level done in the app.js
file.
Enjoy :)