Having stayed behind to protect the museum, you nonetheless had no idea that the Pharaoh's gold was kept here. And where there is gold there is bound to be robbers. But in this case not ordinary robbers, but very well armed and trained mercenaries. Regardless, you still have to protect the museum. But a guard's pistol is not adequate to protect against these mercenaries. Thankfully the museum also kept the Pharaoh's ancient weapons!
Control keys:
E - Change weapons
WASD - Character movement
SPACEBAR - Jump
SHIFT - Sprint
Esc - Exit to the menu
LKM - Shoot