Posted April 22nd 2004, expanded later
The 'rockslide megabattle' is a superb battle against up to 39 enemies in the rockslide area of level 2 - Halo - where Marine survivors are holding out. Easy to set up and rich in tactical possibilities, it's hugely replayable and you could basically think of it as a hidden mini-game. The combat is far more intense than normal, and you'll have great fun fighting alongside Marines or going solo. The battle was actually my original reason for creating this site, though I've greatly expanded my material on it since then.
As well as advice on setting things up and some general battle advice, you'll find an extensive collection of specific battle plans to try, each detailed on its own page. However, I suggest you leave those alone for a while and have the fun of exploring battle possibilities for yourself. Fellow pistol fans should be sure to check out the Far area defence sometime though, for a very special experience. I just had to give that battle plan a special mention.