Ghosts would be spirits unwilling to pass on.

They'd have 100% concealment and be immune to everything except positive energy.

Ghosts cannot make physical attacks but can cast certain spells, and have fear auras.

Normally Ghosts appear to hinder or torment those who wronged them in life.

Yes. Yes. Yes. Then Egon can invent a Wand of Proton Pack and impersonate his namesake :D.

I'd like this make them half orcs with 18 str and great axes!

This is not how D&D ghosts work. They would be inconsistent with already-IG ghosts and the knowledge characters already have about how to fight ghosts.

And, they would be next to impossible to deal with without a DM. Every time someone encountered a ghost, it could be able to chase them back to town, where NPCs would waste their time trying to attack the ghost until a DM arrives to break things up. Pre-emptive reproof: If we could make the creature AI return creatures to their spawn point or just disengage and move away from transitions, we wouldn't have transition kill problems.

What if they were more like mage eaters?

as in.... cast a necromantic spell unwarded and you have a chance of summoning one of these. they mess with you for a bit... fear aura is good for this... and then vanish.

what does this get you? well, basically a chance to kill your entire party by using necromantic abilities. ghost pops out of nowhere and suddenly everyone is feared as they are being beaten on by the monsters you just engaged!

fun times for all!

or just a mage eater with fear aura

If anything has 100% conceal and can only be hurt by positive energy, it won't die. You need to make a touch attack to cast a healing spell or use a healing item on it, with 100% conceal it won't ever happen.

healing circle!

Besides the point that that spell is pretty hard to come across, level 9 cleric or one of the drums, i find it doesn't always hurt undead when cast near them.

Thank you for your suggestion. While it has been considered seriously, we do not feel that something like this would be of benefit to the server in the immediate or forseeable future.

Please feel free to make more such suggestions in future!