The dungeon crawler Minecraft Dungeons is being made by a small team inside Mojang. According to executive producer David Nisshagen there are twenty people working on the game. This is all explained in a short developer diary called Minecraft Dungeons Diaries: Origins. In this video a couple of the developers at Mojang talk about how Minecraft came to be.
The team is in the same building, or even room, as the core Minecraft team at Mojang. This is important for them, as it’s their goal to make sure everything that’s in Minecraft Dungeons could be in the classic Minecraft experience.
Recently it was announced that Double Eleven is working on the console ports for Minecraft Dungeons. The game is set to release early 2020.