Colliding with an NPC triggers some dialogue, then you just backtrack to the door in the center (your progress is displayed there if you look closely). There is something of a checkpoint system but it's not quite as blatant as it might seem. Something super involved just didn't seem necessary for something so small.
Apologies for my vagueness, but I don't like just saying the features flat-out, especially when my account activity is displayed for everyone on the platform. I think it ruins the fun.