The Blue Door

[MadBear]

I'm positive this idea isn't new, but I'd be curious if I can get some advice for a fun device within the world I'm building.

I plan on there being a vibrant blue door that regularly shows up in different parts of town, in different areas, and even in seemingly out of place locations (at the end of the cave appears a virbrant blue door).

Beyond this door lives an old merchant. He collects random artifacts and magic items in his shop that he happily sells to adventurers in exchange for items the players possess. When players leave his house, they often find the blue door no longer where they last saw it.

The thing is that all blue doors lead to his front entrance, and when exiting you're not guaranteed to exit to the same location that you started in.

To make matters more interesting, he blue door has no strong association with time. In fact, when the players first meet him, he's already very familiar with who they are. At a later time, upon entering they'll find him asking more questions then normal since this is the first time he's met them.

How would you keep track of this out of time, out of space door and the plucky old merchant who lives within?

[Blake Hannon]

So, Doctor Who + Howl?

[MadBear]

So, Doctor Who + Howl?

I've seen neither of these things, but I'm sure that their influence was pervasive enough to reach me on this.

[Mechalich]

A glowing blue extradimensional door also features heavily in the Persona series of games - where it leads to the Velvet Room and contains the highly knowledgeable long-nosed master of demon fusion.

As for the use of this device, it's basically a mobile merchant function similar to those found in countless video games where there always happens to be an item merchant in the depths of horrible dungeons before you fight the last boss and so on, you're just making the mechanic less obvious. Its a useful device for the purposes of inventory management - assuming that's a thing that matters in your games - but that's about all it is. Expect your players to treat it as such.

[MadBear]

A glowing blue extradimensional door also features heavily in the Persona series of games - where it leads to the Velvet Room and contains the highly knowledgeable long-nosed master of demon fusion.

As for the use of this device, it's basically a mobile merchant function similar to those found in countless video games where there always happens to be an item merchant in the depths of horrible dungeons before you fight the last boss and so on, you're just making the mechanic less obvious. Its a useful device for the purposes of inventory management - assuming that's a thing that matters in your games - but that's about all it is. Expect your players to treat it as such.

Hmm that's a take on it that I hadn't considered. I wonder what steps could be taken to make it have more depth then just being a mobile merchant of the day.

[GorinichSerpant]

Hmm that's a take on it that I hadn't considered. I wonder what steps could be taken to make it have more depth then just being a mobile merchant of the day.

Give the merchant an interesting, amusing and/or creepy personality. I'd give them a made up accent I can consistently recreate, strong opinions on certain topics, and so forth. Maybe play out the PCs haggling with them if your players are willing.
Give wierd properties to the the items they sells. Maybe the ropes move around like snakes when noone is looking. A hourglass has sand pouring up. Something ages in reverse. The breastplate he sells has a pair of living eyes on it, that give off expressions. The potions he sells make you grow small feathers on your back that shed and get everywhere.
Give the shop an interesting description. Shelves stacked with tomes and bottles of mysterious swirling liquids. Boxes with knick knacks. The dusty smell of attics and old things. A stuffed alligator hanging from the ceiling.
Don't have the Blue Door show up at conveniently-last-room-before-the-boss kind of places. You could either do that by placing the Blue Door on a whim or maybe having a table with locations. When you feel the door should be somewhere else roll on said table, and that's where the door is at the moment.

Terry Pratchett's books have a similar concept in them, you may want to look up the appropriate books for inspiration.https://wiki.lspace.org/mediawiki/Wandering_Shop Here's a Tvtropes link for more examples of this sort of thing, beware Tvtropes is difficult to get out of once it insnares you. http://tvtropes.org/pmwiki/pmwiki.php/Main/TheLittleShopThatWasntThereYesterday

[MadBear]

Don't have the Blue Door show up at conveniently-last-room-before-the-boss kind of places. You could either do that by placing the Blue Door on a whim or maybe having a table with locations. When you feel the door should be somewhere else roll on said table, and that's where the door is at

Yeah, I never meant it to be the shop that showed up before a boss fight.

The whole idea is that is this mysterious out of place and time location.

I love your descriptions, and I'll definitely use those.

In general I was hoping for more advice on running a shop where its chronological timeline was different from the rest of the world.