1. Follow the tunnel to medkits at the end.
2. You're inside the crushers surrounding the Combine Citadel, but not yet within the Citadel itself.
3. Turn left to start a jumping puzzle. Jump from (1) to (2) to (3), then jump to the top of the arrow and slide down to (4), jumping far enough so that you don't slip off to the right.
4. Jump to (1) then follow the ledge to the pipe at (2).
5. Jump to (1) then it's an easy drop to (2).
6. Ascend this ramp to your left.
7. Continue up a second ramp then drop to this walkway and follow it right.
8. Emerge here then follow the ledge as indicated.
9. Follow the arrows.
10. Follow left then drop below here.
11. Drop below then follow the ledge forward.
12. Climb into the pod on the far track to begin "Half Life: The Ride." The pod on the near track takes you to a swift electrocution.
13. The next zone loads, and is completely on rails. This is similar to the introductory tram ride in the original Half Life. You are witness to many amazingly wondrous things, including this never-before-seen species.
14. Hmm, where have I seen this before?
15. Dr. Theopolis voice: "This appears to be a some kind of magnificent manufacturing facility."
16. So this is where the thin trains come from...
17. Egads! Aside from your gravity gun, all of your weapons are destroyed upon your emergence from the pod. Your gravity gun, however, is now supercharged. Heal and recharge at the nearby combo station.
18. Ever feel disappointment because your gravity gun's alternate fire doesn't pick up enemies? Well be disappointed no more! Rapidly alt-fire to pick them up then primary fire to send them flying. Rinse and repeat to churn through a whole squad.
19. Listen to Dr. Breen then supercharge your suit (up to 200) at the station behind you, where more Overwatch attack.
20. Best. Weapon. EVAR!
21. Pause to listen to Breen again. The audio of these monologues sounds awesome on 5.1 systems.
22. Hop over a short fence then toss some Overwatch into the mall art. (If you find yourself suddenly unable to jump, reload from a previous save. It's a known bug.)
23. Ride a lift up then toss a fusion core at the Elite Overwatch. Grab the fusion core from the generator on the left to disable the force field.
24. Fill up at this combo station on the right.
25. Grab fusion cores to defeat the many Overwatch that attack. Pulling the core from a generator to the left will disable the force field.
26. Listen to a third monologue from Breen then head right.
27. Press this button to call the very slow lift.
28. Battle waves of Overwatch as you wait for the lift to arrive. (The lift can be seen descending in this shot.) Hunker down by an energy/health combo station (behind me in this shot) and churn through the Overwatch with your gravity gun.
29. Toss fusion cores at the snipers above.
30. Once the lift is in place, hop on and ride it up, tossing your foes and fusion cores around the shaft.
31. This is a very fun sequence. In fact, this level is the best of the game IMHO.
32. Once the lift reaches the top, pop a fusion core to lower a force field then listen to Breen again. A combo station is to your left.
33. Fight past more mall art then recharge at another health/energy combo station.
34. Listen to another message from Breen then drop to the large corridor on the left.
35. Fight your way down the corridor -- you can use the pods as shields.
36. You've been largely invulnerable so far this level but that's about to change. Time for a stryder boss. Clear out all the Overwatch before engaging the stryder. Use these pods for cover then hurl fusion cores at it.
37. Try to time your attacks to coincide with the pause in his firing sequence. Three fusion core hits and the stryder collapses.
38. Listen to the increasingly-agitated Dr. Breen then pull multiple cores from the generator on the left to lower the force field. Hop through to load the next zone and recharge at a combo station.
39. Time for another ride -- hop on.
40. This is what happens when you spend too much time playing MMORPGs.
41. Continue riding the pod carrier up the Citadel to this magnificent view to end this magnificent level.