Alter Aeon is a multi-player MUD where you never actually have to deal with other people if you don't want to. You can take as little or as much person-to-person interaction as you wish. Players can't screw with you unless you let them, pretty much. And in the few cases where they can, there's protection against it in the rules so that if it does happen, you have a valid way to fight back.

I'm not a huge fan of one of the game's admins, but he's not terrible either. He and I just strike sparks a bit sometimes. Generally, though, it's probably my favourite MUD overall.

I'm not  a huge fan of altar, bores the crap out of me.

Alter is really not a good idea of being able to play solo as you want. You pretty much are forced to group at higher levels or you're useless and/or just won't progress at a decent speed.

There's a reason for the newbie denting stuff though, and having run many, many characters through the islands, I can explain this. I'm not disagreeing with you entirely, Nocturnis, but I do want to provide a bit of background.
Most of the content on the first two islands is extremely easy, and can be blown through very fast. The same is true for the first third or so of Archais, the third island, but the upper portion (level 25-26 and up) gets a little harder. They have made mob damage a little less at very low levels to encourage people to stick around, and they've also lowered exp and stuff so that you don't blow through the game quite as fast. What's been happening is that players finish Archais's entire quest line at level 27 or so, then hit the mainland and get kicked around pretty hard. Or, they don't get kicked around, but they have no idea what to do, no direction (I've been in this boat, I know how it feels). So they're trying to encourage grinding and re-running areas earlier on, because you really didn't have to do this before.
That being said, there is a lot of higher-level content and stuff being released, and the game's max level was just raised from 37 to 38, which is probably a good thing in the long run. They're going to be adding/shuffling skills a bit after they collect data on what the raised level cap does to the player base.
So for me, personally, this is a wait-and-see thing. Depending on your class and build, you absolutely can fight solo at higher levels, if you know where to go. Necros and druids seem to do this best, while clerics and mages seem to have the worst time of it on their own.
Enlightened is a clan which, at last check, is pretty safe and still fairly active, and I personally don't find their members distasteful, aggressive or problematic. They're actually pretty helpful. Being in a clan is not, in fact, an absolute requirement, not even close, but even if it were more insisted upon than it actually is, it's not as if you, say, get extra exp for being in a clan or whatnot. It's not game-defining. It just means you have access to people who probably know the game better than you. And hey, if thre are such resources available, I say take advantage of them if you want. No PVP is forced on you, and in most cases no other disadvantages (like clan dues) either.

Draak here. Just to give you guys a heads up:

We are aware of the problems with areas and quest progression on Archais and the transition to the mainland. Morpheus and Dentin are both working on smoothing out the level progression on Archais, and Morpheus is currently working on direct quest linkage between Dragon Tooth and Ralnoth. From there, Ralnoth is a hub that can take you into Wallachia, Khal-Uktar, Nueva Grenada and beyond. We'll gradually shore up the story lines, but Ralnoth can be overwhelming, as it is nearly three time the size of the largest city on the Westering Isles. With year-end events over, we'll be able to devote more attention to these details.

Regarding high level groups being a required, I personally have been converting outlying group exp zones into autoleveling base solo zones (that is to say, the base strength of the zone is calibrated for a solo character, but it will adjust the level and power of the mobs to match the size and levels of any player or group that enters it). There will always be areas in intended for groups, but there are plenty of solo zones and base solo zones on the high end, too, and more in production.

You can reat your own server if you so desire. But the original places have lots of land still remaining. There just are a lot of ruins everywhere, since a lot of players come in and quit after some time. I've been there from the start. Khufu possibly doesn't like nagging, but that's a thing. I've started my empire countless of times over and over again, because I end up quitting for months and everything just falls into abandonment, but never have I had any problems with finding that piece of land to build and found cities. Can't we all just get along?