"ID Tech is a legendary series of separate game engines designed and developed by id Software.
If you want to learn more about history of this engine check out this links:
http://www.ign.com/articles/2011/04/28/a-history-of-id-tech
https://upload.wikimedia.org/wikipedia/commons/8/85/Quake_-_family_tree_2.svg
https://en.wikipedia.org/wiki/Id_Tech

Track List(All rights on this music belongs to their authors):
1.Wolfenstein 3D OST - Get Them!
2.Doom II OST - Running from Evil
3.Quake II OST - Descent into Cerberon
4.Doom 3 OST - Main Menu Theme

P.S Yes. I was using source ports. Without them it is impossible to capture such old games. At least with ShadowPlay."