This is a lowly .bsp map file for TTT in gmod.

Extract the .bsp file to your common/garrysmod/maps folder within steam (c:/program files/steam/games/ or the filesystem you have set up) to find it in your map menu.

You can load the map in sandbox if you wish to explore, or ues ttt with the following console commands to allow you to test the traps and buttons:

sv_cheats 1
ttt_minimum_players 1
ttt_debugprevent_win 1
ttt_force_terror

The last command spawns you as a traitor.

Enjoy