Spiral path megabattle
Posted September 20th 2004, expanded later
If you like snow and you like your combat intense, you're in the right place. The 'spiral path megabattle' is something you can set up in level 5 - Assault on the Control Room - in the place where you meet up with a group of Marines that get attacked by Hunters. By getting a mass of enemies chasing after you from previous areas, you can end up facing a big angry mob here, potentially numbering 61 on Legendary, 53 on Heroic, and 50 otherwise. The confined area may not permit the same range of tactical possibilities as the rockslide megabattle, but on the other hand you've got rocket launchers and the opportunity of setting up blockades, and the fighting is every bit as intense. So don't miss it!
I think quite a few people will have stumbled into this megabattle of their own accord, because the potential is there any time you skip through the previous area without hanging around to blast much. For example the scenario was enthusiastically mentioned in an HBO forum post by SketchTeno back in April 2004, where it was already old news to Captain Spark. I'd bumped into it myself by then but hadn't fully realized the potential, and I was so busy with the rockslide megabattle that it was another few months before I followed up on things, eventually posting an account in September 2004. But I've expanded and refined things a lot since then.
The core material here is in the first four sections. Two additional sections concern making the enemy attack or collect in one big mass for intensified battles, plus the business of adding extra Marines to the battle. But those things entail extra work and complication so I suggest you leave them for later.