65 Security Keycards are hidden somewhere in the Black Mesa Research Facility. Can you find them? Remeber that one time when doctor Kleiner forgot the keys to his office back in Black Mesa, so Gordon and Barney had to figure out how to get in through air vents? Well, that was not the single case. And probably that was not so unintentional... Kleiner really likes to test his colleagues' abilities, so this time he set an ultimate challenge for Gordon Freeman. Doctor Kleiner hid 65 security keycards all across Black Mesa Research Facility, and it is your task to find them all! In order to assist you Kleiner also tweaked your glasses a little bit adding augmented reality function. When you see a big yellow exclamation mark somewhere in the facility, it means that a security keycard is nearby.
