Obsidian has confirmed that tilesets will only be used in in-door areas. Outside areas will use height mapping.
“A tileset is a collection of tiles which follow a common theme. They allow module creators to...Tileset
“This tileset is used for the last dungeon of the official campaign, featuring dark stonework...Shadow Fortress tileset
“This tileset is used for the ruins of the Illefarn Empire, featuring ornately decorated...Illefarn tileset
“This tileset is used for castles (such as Castle Never), or any other extravagant hall. This...Standard Castle tileset
“This tileset is used for the dead....or undead. It can be tinted but has no meta tiles. This...Crypt tileset
“This tileset is used for most indoor structures like townhouses, taverns, and shops. This...Standard Interior tileset
“No adventure game would be complete without dark caverns containing all manners of scary...Caves tileset