Q: How do I open doors?
A: Face the door and press your "use" key, by default "E."

Q: How can I get through these long hallways when there are snipers covering them?
A: Try a smoke grenade!

Q: How can I rotate between bombsites quickly?
A: Try exploring the vent system!

Q: How do I use the Elevator?
A: There are two buttons inside the elevator that can be used to make it go up or down. There is also a hatch that can be broken on the top of the elevator car, and ladders in the shaft that can be used to climb up or down if the elevator car becomes stuck.

Q: How do I open the West door to the Lab (Bombsite "A")?
A: There are two buttons in the Security booth, and one button inside the Lab which can be pressed to open the West entrance to the Lab.

Q: Where is "Middle?"
A: There is no explicit "Middle." The interior areas labeled "Mess Hall," "Lockers," "Mechanical," and "Connector" all occupy equal significance in controlling the center of the map, and rotation between spawn areas.