The story of SE basically picks up a couple of months after the end of Deathkings. The story of The Serpent Power picks up 20 years or so later. This means we have a trilogy:
1) The Chaos Sphere (TCS): the original Hexen and Deathkings story with maybe some smaller additions. It's basically "Hexen reloaded" with extras like more "cutscenes" of some kind to make it a more story-driven game, maps revamped with Vavoom features to look cooler (for those who haven't seen it yet, check out the Winnowing Hall remake by Firebrand, it's awesome), RPG additions like in KMOD (but differently implemented), inventory, NPCs, shopping possibilities, a hidden base you can return to, etc.
2) Scattered Evil (SE): a couple of months after Korax was defeated and his minions scattered. The story leads you into finding out about the secret cult that wants to resurrect Korax, and your task is to destroy the cult (planned end boss was a uber-Heresiarch that would not only be much stronger than a standard Heresiarch and have some extra spells, it could also manipulate the environment like Korax in the original Hexen and it could also teleport around etc).
3) The Serpent Power (TSP): Picks up like 20 years after SE, it's a "next generation" story. Of the 3 heroes of the original Hexen, only Daedalon still lives in his secluded tower, and as a young apprentice/whatever you go to him to find the Serpent Power. This story is a bit deeper and more "thinking", it has philosophy and religion stuff in it too - the serpent power is just a word, but everybody understands something different behind it. For the mage, it's a magical power, for the cleric, it's a spiritual power, for the fighter, it's a physical power. Thus, you can play the game 3 times and have a completely different story and quests.
So basically we are making a trilogy, i.e. we release 3 RPGs, not just one. Publicly, there is still mostly talk about SE, but SE is actually the middle part of the trilogy, the first part to be released will be TCS. That said, work can proceed parallelly on all 3 parts, as a lot of it will be common. Also, a somewhat detailed storyline of both SE and TSP needs to be written before TCS can be finished, so we can add hints and cool references to later parts, that's always appreciated by gamers.
Regarding maps, the Korax RPG trilogy is gameplay oriented and wants to accomodate both the RPGer and the FPS guy. Meaning there'll be a main storyline with relatively little in the way of puzzle solving or running around for quests. Instead, it'll allow you to wade into the thickest of the fighting and muscle way through the game. It'll of course need a lot more skill in FPS games as you will be a much lower level than you'd be if you'd have taken all those side quests and explored everything, but it'll be a shorter, directer and more brutal game. Or if you are into long RPGs, you can explore zillions of dungeons, go through a lot of sidequests etc and by the time you face bosses on the main storyline you'll be a much higher level, having more formidable attributes, spells and weapons, meaning you won't have to be that good with shooting without being shot at. <!-- s;) --><img src="{SMILIES_PATH}/icon_wink.gif" alt=";)" title="Wink" /><!-- s;) -->
This also means there are two kind of maps in the trilogy: the main storyline which is storybound and offers the best-looking scenery, and the optional maps which simply need to fit into the world of Hexen. This latter is the vast majority of the maps, meaning anything you make and is Hexen-like can be used in the game, nothing needs to be thrown out. It can also very well happen that such a casual map is so outstanding that it'll be migrated into the main storyline. So I'd say just map away.
One thing that IMO should be extremely totally redone for TCS is the castle of Korax (Dark Crucible), it's lame and ugly and boring in the original Hexen. I think it should be replaced by an awesome architectural marvel that still has all the quirks of the original (i.e. Korax controls the environment, you never know where you step into your death). Also, while Firebrand has worked on the first hub (Seven Portals) and I still plan to work on the 2nd (Shadow Wood) hub, the other 3 hubs are still uncounted for, so every mapper is currently free to make new maps from scratch and/or alter original Hexen maps so they look better (just don't go extremely crazy, performance shouldn't drop to the cellar).
Oh yes before I forget, one important thing is that many smaller maps are preferred to a few large ones. If you have an idea for a big dungeon or whatever, try to split it into parts. Since Hexen is not linear and you can go from map to map and then back, you can e.g. make a dungeon where you go through a door, are in another map but still the same dungeon (except for the loading screen you wouldn't even notice you're in another map), then go up some stairs and go through another door and arrive back in the previous map, just on a balcony 30 feet higher. <!-- s;) --><img src="{SMILIES_PATH}/icon_wink.gif" alt=";)" title="Wink" /><!-- s;) -->
If you have further questions, just post them here, I'll answer them all. <!-- s:) --><img src="{SMILIES_PATH}/icon_smile.gif" alt=":)" title="Smile" /><!-- s:) -->