The PHD file extension is related to the Tomb Raider computer game and used for its game level files.
PHD file extension - Tomb Raider game level file
What is phd file? How to open phd files?
File type specification:
The PHD file extension is associated with the Tomb Raider 3D third-person shooter adventure computer game.
Tomb Raider was developed by Core Design and published by Eidos Interactive. It was originally released in 1996 for the Sega Saturn followed shortly thereafter for MS-DOS and PlayStation versions.
The *.phd file stores game level.