Well, the system I intend to use on my MUD is equipment-based. Each piece of equipment has its own set of abilities that it gains more of the more you use it, and your character has access to only those abilities present in your equipment. Needless to say, this is my personal favorite.
The only other major advancement style I've seen before is custom classes. Basically, each character picks 3-5 skill trees to create their own class, or chooses a default class from a list. From there it usually progresses like a single class system.
We're in the process of trying to change our mud to multi-class instead of smaug style (single class). I've seen remorts and never yet seen one I like. It just really bothers my sensibilities to work a character up to avatar only to essentially start over with a "better" class (that I usually have trouble seeing a real advantage to anyway), no matter how you structure it. And the classless/levelless, etc systems just don't really appeal to my instinctive sense of competition at all. ;)
Of course, it's just my opinion, but on my own mud my opinion carries a great deal of weight. ;)
Yeah, once had a modified limited remort system on a 100level mud. Basically, at level 50, you were forced to "remort" but instead of resetting the level it just changed the class. Level 75 required another remort…
So you could go from… warrior - knight - paladin
Wasn't hard to write… but you needed to be careful that the new class had all the previous classes skills. Although for some skills, we tended to increase the adepts with the higher classes.
mmm personaly im a big fan of classless/multiclass/remort although with remort you often have to add stuff to give one an advantage to the whole remort prossess or it becomes uesless mind you i have a whole system in my head for a remort/classless mud planed out I just dont have the skill to create that world yet so im starting off small with the other words i wanted to make ( a multiclass mud )
You start off classless, with access to various weapon skills, fighting styles and talents, but are eventually able to earn a class. This class provides additional powers, but you still retain access to all of the common abilities.
Each class has around 20 powers, and each character can choose 3 primaries, with a smattering of freely selected ranks in their other powers. For example a newly classed character can raise their 3 primary powers to rank 10, and have another 10 ranks divided however they wish among their other powers. This means it's more like "create your own class", with the classes providing more of a thematic framework for those powers - two people of the same class can end up with completely different types of character.
At certain points in your development you're forced to select a subclass in order to continue advancing, and these branch out into different areas of specialisation. Each subclass provides bonuses to certain powers, and gives various other benefits, although they're still basically the same class.