Marineless first ground battle
Posted July 21st 2006 (originally as part of the seven-extras piece), updated later
Associated movies
Here's a little novelty you can arrange by doing something a bit different at the end of the trick for getting seven extra Marines. After triggering the battle by going through the door, continue inside to the lift. The fledgeling battle meanwhile gets frozen at the loading point I think. As you reach the lift the third room gets populated. If you now return to the battlefield, you'll find that there are no Marines. There are just covies mulling around. Often they didn't even spot the Marines before the battle got frozen, in which case they're still completely casual.
Instead of coming straight back when you get to the lift though, I suggest that you first ride up in it to get a checkpoint. That causes normal checkpoint structure to be resumed, and as such you'll trigger a checkpoint in the passage leading outside when you come back down. That enables replaying, if you want to have some fun with the novel situation.
You could charge into battle as usual of course, but another approach is to try and be stealthy, exploiting the covies' generally non-alerted state. In particular you can use a sniper rifle and rocket launcher (once grabbed) to pick off most of the covies from distance.
What happened?
Why are there no Marines? Here's my understanding. When you triggered enemies in the third room, the game also did what it usually does along with that, namely removing any Marines from outside. The game is expecting that you're on your way down and out, and that three new Marines will be created later as you trigger the battle. However, the battle has already been triggered, so no such creation occurs.
Tailing the patrolling Elite
On the far side of the battlefield there's an Elite whose default behaviour is to casually patrol. As part of that, he potentially walks a long way over towards the door (see pic) before turning back, something you'd normally never see. If you've got rid of the other covies (e.g. mostly with sniping and rockets) and he's still patrolling, you can have some fun by closing in and tailing along right behind him. See how long you can keep it up before being spotted. The difficulty may depend on difficulty level and on whether he's red or blue, but I haven't checked into that.
You need to keep an eye on his head angle, because if he looks to the side, that's when you're in the most danger of being seen. Essentially you should try to keep behind his head, rather than behind his body.
When you're eventually spotted, he'll probably take a swipe at you and may do a bit of shooting too, but soon he'll run to man a Ghost. If you tag him as he's boarding, a spectacular explosion often follows. Another option: man the other Ghost and have a Ghost duel!
Plasma pistol sniping
If the patrolling Elite gets spooked and boards a Ghost but hasn't actually spotted you, he tends to just hover there. At that point there's scope for blowing up the Ghost with some plasma pistol sniping. See my picture capturing an explosion after switching to a zoomed pistol. This can even be done from the exit passage. See what else you can do with long-range plasma fire. Among the possible targets are some covies moving in from the end of the battlefield, and there's also the Wraith.
Step right this way
Something I did one time was weaken an Elite until he got mad and came after me. When he reached the passage he initially just stood there, but by making him continually swipe at me I was able to lead him though the passage and the room and into the lift. It was surprisingly easy but it probably helped that he was only a blue. We started going up but I accidentally fell down the lift while dodging a swipe. Who the heck designed those stupid lifts? So I got another blue and had another go.
This time the lift section went ok and I started getting him towards the next room, but his behaviour seemed to have changed. He was more hesitant about swiping and I had to give him a lot more opportunity, during which he often used his plasma rifle and did sideways dodges. So my progress was a lot slower and I had to be careful about my health (this was on Heroic).
After maybe ten minutes I got him out onto the bridge, and it was there that I wished I hadn't shattered all the glass panels on the upper deck, because the holes were clearly going to make progress even slower! I'd had enough by then, but with a bit more work maybe you can get him back to the start of the level. Go try it out if you're up for it.
Fun from the bridge
Instead of returning to the passage after going to the lift, you could continue on up to the bridge, from where you can lob grenades and use the tremendous range of the plasma pistol to destroy the Wraith and kill some ground troops - just for a bit of mischief. Retreating up to the bridge is something you can do also with a normal battle incidentally, in which case it'll still be raging below. But you'd have more fun up here with a sniper rifle and rocket launcher of course.