I walked to the edge of the world and cannot move any further, as intended. Then I jumped down from a cliff and climb back, and now seems like I'm on the other side of the edge! I cannot go back (but I cannot move away too, I have just a "safe area" of 5x5 tiles that I can use).
edit: I managed to move back by doing the "slide" thing on the top of the cliff. I don't know if it's how it should work.