Welcome to the lab Altejjra – we're glad to have You as our new employee. Our research laboratory is engaged in advanced developments in the field of security and management. To an internship with us is a great success. However, from the first day of Your work, something went wrong: noise, commotion, falling debris, the building becomes a real trap, as You are trying to get to a safe bunker. It's time to look for the crowbar and run to fend off headcrabs, only here in the dark waiting for something strange to come across him in no event it is impossible – it would mean certain death. To leave the floors, You have to collect certain items – for example, a key card that will unlock the exits. So what is this creature that attacked the lab, Altara? And if You can escape unharmed?