Black mesa

black mesa is a company in half-life and half-life

black mesa is the company that caused the xen alien  invasion. in half-life the game takes place in black mesa.black mesa had made many advanced items such as the teleporter to xen and the displacer. in half-life 2 there are only lines about it. then you go to black mesa east

which is not the real black mesa, but eli's HQ.