File formats - Game3DEE/darkstone-tools GitHub Wiki
Inside the main MTF files are many different files in different formats. This page functions as an overview of which formats are used for what.
The descriptions below explain the contents of the format, not the format itself in detail. If you are interested in the exact bits and bytes of that, check out the Darkstone Web sources for exact definitions of these formats.
O3D
This is the 3D model format for all static meshes. It is used for all the "tiles" used in the game. For example, there are tiles for the corner of a house, for a straight wall, etc. Several combined together make a single house, and because of these tiles you can build long houses, short houses, all with the same tiles. There are also models for trees, tables, etc.
CDF
These are the "room" files. For inside dungeons, these are generally rooms, but for the places above ground, they are simply self-contained areas, like a lake, an island, a village, etc. The CDF format contains all tiles used in the room, all "traps" (the term used for any intractable content, like loot to pick up, but also containers, traps, and switches. Even the torches on the walls in the dungeons are traps. It also contains a grid to keep track of where you can walk, and where you cannot. Lastly, it also contains a list of "monsters", NPCs that do/can spawn.
SPT
These are script files, defining the quests and their related objects. It specifies which "rooms" (See CDF above) are part of which quest, which items/npcs are there, etc, etc. See the Scripting section on this wiki for details.