I am squarity-in !
Like the previous Ludum Dare, I will be using my own game engine : http://squarity.fr , which allows you to code and play 2D grid-based games in python, directly in your navigator.
This time with real display of exception and traceback when your python code fails. Woot.
If you're interested, you can play this dumb soko-ban game here : http://squarity.fr/#fetchezgithubgistdarkrecher/aa3e1338998cc2a20a030011fbca9ce2/raw/sokoban-tuto.txt
To explain how the engine works, the game source code is heavily commented ... in French. Sorry for not having translated.

Fetchez la vache and let's get slaughtering !