Untrusted is a fun and quite different browser game. You play by modifying parts of the game's source code, in order to create a path from your characters position to the level goal. It starts out easy enough, on a map where only a single wall is blocking your path to victory. On the later stages, you'll probably have a harder time one-shotting your way through the maps (unless you're some sort of genius).
We promise it's a perfect time sink for lazy, December Sundays. Let us know on Twitter when (if) you get to the very end (#dotchristmas).