Tunnel onslaught
Posted January 27th 2008
Once past the last of the enemy vehicles, head down the highway in a Chopper or Warthog and use it to bypass the blockades, after saving an approach checkpoint for replay purposes (see later). You can easily bypass the first blockade by driving up a narrow grassy slope to the left and launching yourself off. Reach the tunnel barrier and run through, then try to survive from within the tunnel. Usually all but one of the Brutes you've bypassed will close in on you (see Enemy retreat to the final barrier for part of the reason) and things are likely to get mighty hectic! I think you'll have the most fun on Easy, but Normal is also viable. Best forget about Heroic; you'll have trouble even reaching the barrier alive!
For the approach I'd recommend a Chopper over a Warthog as it's less violently affected by Brute shot blasts and has a useful ability to launch up over things.
Make sure you're loaded with grenades. Jetpack Brutes often hover your way and can be easily tagged as they land. As for weapons, bear in mind that you could be carrying a full fuel rod gun or full Brute shot if you want one. Also, there's no cover in the tunnel so it's a good idea to bring along a portable shield, or a bubble shield if you prefer.
During the battle, killed Brutes sometimes drop trip mines. If you pick them up and deploy them quick, they're quite likely to do some nice damage as further Brutes close in. Or maybe wait to deploy one as a jetpack Brute is coming down. Nasty landing!
Sometimes you get some Brutes who seem a bit standoffish and you may have to go out to get them, but never mind, it's a bit of variety.
Who dat?
It's terribly dark in the tunnel and sometimes it's like you're shooting at silhouettes as the Brutes come in from the light. Your flashlight won't make much difference, but it might be worth turning up the brightness on your TV.
Barrier exploitation
You have the option of bringing down the barrier as you pass through, but you may prefer to leave it intact to begin with so it protects you for a while, giving you chance to recharge your shield before the onslaught. As the battle continues, the barrier will continue to protect you from enemies on the other side, thus reducing the amount of fire you take. But at some point when you're feeling on top of things, you may like to bring it down (which you can do from distance with a grenade or a few shots from a fuel rod gun or Brute shot) so you can start opening fire on enemies earlier. If you brought along a sniper rifle or beam rifle, that could actually be an integral part of your battle plan.
Replaying
The way I've described things so far, you tend to get a checkpoint part way through the battle, which is annoying as you won't then be able to revert to replay. However, you can always get back to your saved approach checkpoint by exiting to the dashboard then reloading.
Normally the final cutscene only starts up when all enemies are dead, but sometimes it starts up prematurely, when there are still plenty left. On occasion I've even had it start up practically as soon as I've arrived at the barrier and destroyed it. I haven't managed to identify exactly what's causing this, but it doesn't seem to happen very often so it's not too big a problem. However, definitely avoid destroying the turret after the barrier is down, as that would probably trigger the cutscene.
If the cutscene does start up, it's still possible to revert to the last checkpoint (possibly your approach checkpoint), but only if you do it instantly. If you're not quick enough, the game will start loading the next level and you'll have to exit to the dashboard and reload as usual.
Alternative set-up method with easy replay benefit
Rather than driving right up to the barrier, you might prefer to head for the two big green containers on the right. You can dismount and use them for cover until your shield is recharged, then sneak out and run through the barrier. This may be the best way of getting though in one piece, on Normal or higher.
There's potentially another more important benefit though. If you stay hidden a few seconds (e.g. back near the oil drums), you tend to get a checkpoint. This can now serve as your battle start checkpoint. I find that once you've had this checkpoint, your subsequent battling won't be interrupted with a checkpoint (possibly because this checkpoint is the one that might have interrupted) hence you can revert to replay with no trouble. That makes things a lot more convenient.
Vehicle defence
On Easy at least, it's viable to quickly bring down the barrier then drive into the tunnel, to defend using your vehicle. You can even do this with a Wraith, blasting the barrier as you approach. Getting a Wraith past the earlier blockades is clumsy but doable. With a Warthog or Chopper you'd need to briefly dismount to destroy the barrier.
Once in the tunnel, defending with a Chopper is rather clumsy and you have to be careful that you don't get boarded (you can likewise get yanked out of a Warthog, as can any Marines), but it's quite good for running over Brutes using boost. With a Warthog you'd either want to have a gunner along, else be alone and switch to the chain-gun once deep in the tunnel. But if you do man the chain-gun, you have to keep Brutes back else they'll yank you off it. Because of this, overall I'd say that the Wraith gives the most fun for a vehicle defence.
Marines
It's possible to bring along Marines in a hog, but even if you can get it to the barrier without being overturned by Brute shot blasts (very aggravating), the Marines seem to dismount and remain outside the tunnel. They'll provide some distraction for a while, but even on Easy, they'll soon be dead. Actually I wouldn't recommend bringing any Marines along - or having any trailing behind you - else they might take out the turret and cause the cutscene to start up, ending your battle.