Alyx will lead you through the rooftops and into Dr. Kleiner's hidden lab. Here, you'll be reunited with Dr. Kleiner and D0g. You'll receive your iconic Crowbar, your first weapon. Kleiner will attempt to teleport you to Black Mesa East, but a mishap occurs, briefly teleporting you to various locations, including the G-Man's office. After the teleportation failure, you'll be back in the lab. The Combine will be alerted to your presence. Alyx will then lead you out through the back.
Half-Life 2
Kleiner's Lab
Follow Alyx into Kleiner's Lab in Half-Life 2 and receive your first weapon, the Crowbar, before a teleportation mishap.