Hey. I've been seeing people saying different things happening on day 13, usually that the customers come in and almost immediately leave. This hasn't happened for me yet, but on both times I played the game, on day 13 the customers just full stop coming into the store. On the first playthrough I wasn't entirely sure when it began but it was around day 13 and on the second playthrough I paid attention and made sure it was 13 and not some other day.
What happens is a npc outside the shop stops moving. I have no idea if they are a random NPC or a customer. But one of them just becomes a vegetable. For some reason when this happens the customers just stop coming. From day 13 to 16 no one came in the store. The malfunctioning npc can be pushed a little but they don't go in the direction you try to push them most of the time.
System info:
Windows 7 64-bit
Game version 0.0.7