During the development of previous Legend of Zelda games, Nintendo often added special test rooms to debug builds. These test rooms were usually independent maps not connected to any other area in-game and contained various objects to test different aspects of the game. Here are a few examples: Room 118 - "test01/Jungle Gym" in Ocarina of Time contained a range of coloured tiles representing different terrains such as stone, mud, and grass. There were different structures like ledges and slopes at varying gradients as well as water pools. This was probably used to test the physics of Link's movement and how he would interact with different environmental properties. Room 119 - "Treasure Chest Room" was exactly what it was named for: it contained chests with every piece of equipment obtainable in the game plus miscellaneous things like Heart Pieces and bottles. There was also another area that had flying tiles much like the ones seen in the Fire Temple. This was used to test the inventory and how items/equipment would interact with other objects. Room 121 - "syotes2" was a hallway that had pillars and would spawn a Stalfos when Link walked to the centre. This was used to test targeting and combat as well as how obstacles like pillars would affect things. Room 118 was also ported to Majora's Mask and Majora's Mask 3D, with the latter including it in the retail build of the game. It can be accessed with a romfs patch. Wind Waker had a similar physics test map as "Room 118" in Ocarina of Time. Anyway, back to Breath of the Wild. When I played the Master Trials or entered a shrine, my first impression was that these rooms resembled the debug maps from previous games. Each level was a room that was isolated from the main game world and therefore events occurring in them would not interfere with the overworld or plot flags. The shrines tested how Runes could interact with the physics of the game while the Master Trials would test environment effects such as heat/ice, inventory behaviour (since you start off with an empty inventory), enemy AI, combat, and how all of the above would interact with each other all in a relatively "sandboxed" environment. Each level of the Master Trials would present the player with a fixed scenario that had many open-ended solutions and the levels would increase in complexity with more and more interactions between the environment, player, and AI. At least, that's what I think. We might never know the development process behind Breath of the Wild, but I wouldn't be surprised if the shrines were actually modified versions of their debug rooms.