I had a lot of ideas for plotlines that I never wrote into actual play for one reason or another -- usually because they'd have been better off in another game (or as their own).
It actually reminds me of another defunct idea of mine for D2, WAAAAAAY older than everything else I've mentioned thus far. I remember had been experimenting with a Descent room generator thingy (I forget it's exact name) that could auto generate shapes like spherical rooms, etc. One of the shapes it'd do was a helix, the length depending on how many cubes you inputted into it using, and I thought that was pretty cool, and I decided I wanted to use that for something, and after some thinking, though that if I overlayed the D2 secret portal texture over some other scrolling texture (say flowing water) for the interior of this thing, I could make a sort of wormhole-like effect that "flowed" with the player's movements through it. I then devised plans for a brief D2 level set where the player finds this helix-shaped wormhole (referred to as a "quantum helix") that drops the player off in distant space where it has to fight through one or two infected mine-like places before finding an alien spaceship that, upon infiltrating, finds can artificially create the wormhole and use that to stage a return trip back home.Very story-driven and sort of a D2 mix of Entropy II and D3's Alien Territory in feel.
Back when D2X-XL was first showing off it could do in-game teleporters now, I had thought about doing a level that had a central "hub" of four (or more) teleporters, with each one leading to a different terrain environment, like a water environment, lava environment, ice environment...each serving as little pocket arenas for players to chase each other into and combat. Always liked the idea, but never got around to actually sitting down and starting work on it. I also had concerns that such a level may not perform well in a network game, but seeing I never got started on it, I never got far enough to find out if it was an unfounded fear or not...it probably wasn't, but you never know.
Oh yes, I've been keeping tabs on that thread Hunter