1. A dune buggy under an electro-magnet. This level looks promising.

2. Don't forget the ammo in the back of the buggy. Ready your gravity gun before hopping in.

3. The magnet malfunctions and the buggy lands upside-down. You're surrounded by antlions, reminiscent of the bugs in Starship Troopers. Keep moving while you use the gravity gun to upright your buggy.

4. Hop into the buggy and drive hard. The bugs keep spawning so don't even try to clear them out. This ramp is your cue that you're heading the right way.

5. Follow the road a short distance and you'll soon encounter a second, much larger ramp. This time you'll need to use your turbo to clear the break in the road.

6. Grab the supplies on the left before entering the tunnel ahead to load the next area.

7. Bear right as you exit the tunnel and drive down toward the beach below.

8. You'll soon come upon the first of many thumpers, themselves reminiscent of the thumpers in Dune. Unlike those, these thumpers repel the beasts rather than attract them. Smash through the fence ahead by using your turbo to continue.

9. A short distance later you'll want to bear right to come to the next thumper. Exit your buggy to retrieve supplies from the shed ahead, then ramp up to the building on the right as you ready your close-range weapon of choice.

10. Mine is the .357. Three CPs are inside, as are more supplies.

11. Take a look through the spotting scope to spy what appears to be G-Man himself across the way.

12. Drive a short distance, hugging the coast. You'll come to the next thumper. Defeat the troops surrounding it then find more supplies inside.

13. Follow the shoreline a bit farther then turn left at this thumper.

14. The compound ahead is your destination.

15. Exit your vehicle and follow this nice man to the basement.

16. Inside you'll receive a briefing - and this rocket launcher.

17. Just in time, too -- a gunship has appeared outside. You'll need plenty of rockets like this one to bring down the gunship.

18. Try to rotate your laser sight - the red dot - to spiral the rocket and avoid your target's defenses. Once your rocket is close to the kill, paint the target with the laser. The rocket will home in on the laser and strike the ship if you are steady enough.

19. Take cover in doorways like this as you search the outbuildings for ammunition and medkits. Your comrades will also provide you with supplies - a refreshingly helpful role for NPCs.

20. After a handful of solid hits the gunship is brought down.

21. Return to the Colonel and he tells you he'll raise the gate so you can continue to Eli Vance's hideout. He also warns that the bridge stronghold has most likely been captured by the Combine.

22. Grab any remaining supplies then head out this gate after it's opened by the man on the right.

23. Leave the road here and follow the path right to load the next area.

24. Antlions attack as you drive under the aqueduct.

25. Pull up to the ramped planks and park here. The thumper on the left is deactivated -- hop out of your buggy and turn it on first. Ready your pulse rifle and follow the troops up that ramp.

26. Don't miss the supply crates by that door ahead as you fight your way through the troops.

27. Climb this ladder.

28. The crane on the left is your objective.

29. Up you go.

30. Take out this solitary sniper then climb another ladder to the cab.

31. The crane's controls are displayed for you to see. What you want to do here is maneuver the crane to pick up the buggy, just like at the beginning of the level.

32. Now swing the crane around so that you knock over the bridge segment as shown here.

33. Time for the real fun. Soldiers pour out from the garage, but you can smear them on the docks with your crane. Drag the buggy, the barrels, and shipping crates around to finish off your foes. Brilliant fun!

34. Return below and cross the bridge. Fight your way into the garage.

35. Enter the office and throw the switch (inset) to open the garage door.

36. Hop back into your dune buggy then drive a short distance to this warehouse. Hit your turbo button to jet up that ramp ahead and crash through the large window.

37. Very satisfying.

38. You'll soon come under attack from another gunship. Don't fire upon it. Instead, hit your turbo again to clear the break in the road ahead.

39. You'll need to use your rocket launcher to bring down the gunship, but don't exit your buggy until you get to this area littered with vehicles.

40. An unending supply of rockets can be found in the white van.

41. As before, spiral your red laser dot then focus on the gunship to aid the rockets in hitting the target. Duck between the cars for cover.

42. About four or five good hits should bring him down.

43. Use your gravity gun's primary fire to clear the road. Drive your buggy a short distance to find supplies in this blue van (inset).

44. Another tunnel, another zone to load.

45. The biggest danger you'll be facing at this point is driving off the cliff. These electromagnetic mines cling to your vehicle, making it difficult to maneuver. Your gravity gun will pull them off with ease. Toss them into the water below.

46. Keep driving and you'll soon come across this optional diversion. Fight your way into the buildings on the right for supplies, or just rush past them on your buggy.

47. Around the next bend you'll find some Overwatch troops unwisely milling about around several explosive barrels.

48. Use your gravity gun to clear a path around this tanker. Grab some ammo and a crossbow from the hill to the right (inset).

49. Your next challenge is this force field. Take out the guard on the billboard before dismounting the buggy.

50. Defeat the troops and find supplies in the buildings. Notice that the car is wired to the force field.

51. Use your gravity gun to push the car, unplugging the force field.

52. Alternately, use secondary-fire to pull away these wheel blocks and the truck will drift backwards and snap the wire.

53. Yup, you guessed it - another tunnel, another zone.

54. Pass a solitary guard and come to this fork in the road. The path on the right leads to some buildings and the path on the left leads to a large bridge -- the one mentioned by the Colonel.

55. If you drive onto the bridge you'll find that the way is blocked by force fields.

56. You'll need to get to the lower decks of the bridge, but first clear out the buildings of enemies (and supplies). A good way to start is by tossing grenades and sniping with your crossbow.

57. An infinite supply of rockets can be found in that crate ahead.

58. Use your gravity gun to move something like this small table to hoist yourself up these stairs. Be careful as a toxic zombie lurks up there.

59. Another toxic zombie lurks under the floorboards of the buildings that lead to this door. You can avoid him and just climb to the ledge above-left of the door then drop down.

60. The next area loads and you find yourself under the main deck of the bridge. This is not quite a jumping puzzle but more of a walking puzzle. The less jumping you do, the better. Walk along the girders to the small office ahead, being careful to avoid a barnacle on the left.

61. This bridge zone has some of the best atmospherics I've ever experienced in a game. The sense of height, combined with the vibration of the bridge plus the sound of the wind create a remarkable sense of place. Exploration here yields rewards of supplies and great views like this.

62. Climb a ladder to this position where you can launch rockets at the forces ahead then replenish at the crate.

63. The path ahead is fairly straightforward but you'll be met with strong resistance at the end. You'll find this force field up some stairs as you reach the other end of the bridge.

64. Use your gravity gun to unplug the force field, or just shoot it.

65. Fill up at the health and energy stations on the right then push the switch on the left to deactivate the force fields on the main bridge deck.

66. You've got to make your way back across the bridge, but now there are more troops - and a gunship - after you.

67. Rush back to the rocket supply crate and engage the gunship. There are medkits in the small shed by the supply crate.

68. Once again, spiral then paint the target with your laser and a handful of direct hits will bring him down.

69. Leave the bridge then fight your way past the feuding ghoulies to the roadway above.

70. Clear the area as you work your way back to the buggy, then grab any remaining supplies from the buildings below before leaving.

71. Uh oh. The force fields are down and you can now travel across the bridge, but this train comes steaming towards you. Start backing up as soon as you hear its horn.

72. Let the train pass then resume your trek across the bridge. Another force field blocks the train tunnel ahead, but you can veer left to drive through the automobile tunnel seen far-left to load the next level.