The directory OBJ_MTL contains the OBJ with MTL and TGA files.
The directory SOURCEENGINE contains the compiles valve object.
The model is compiled using HL2DM. It could be used in any
other game, based on HL2DM engine and up.
Copy the materials and models into your gaming folder. ie:
<STEAM>\SteamApps\common\Half-Life 2 Deathmatch\hl2mp
The model appear named : mlp/watertowerarea2
In gaming you must include it as an prop_static.
It does NOT contain any collision model.
Use noclip brushes or place ladders into the model, as you like.