I am not talking about the actual programming as I have no skill or desire to make one, although I might play one.  Instead, I am listing some features I would want to see and how would you handle certain events.

1.  I would want to see immortals and mortals interacting with each other in different ways.  There is a secret society of immortals who would have to keep their identity secret from the mortal players.  I would include a more aggressive version of the Watchers and maybe some other groups like an Inquistion type group, organized crime, etc.  Immortals expose themselves when they fight or use certain abilities.  In other words, I want two different worlds going on at the same time.

1a.  Immortals have to stay in the cities.  They would have a generic sense power which would tell them general location but if a bunch of PCs are standing together, you don't know who is who.  However, if they are by themselves, then you know who they are and can challenge them to a duel.  I would make it so you couldn't spam someone with duelling requests.  

1b.  If you do duel, I would put in some cheats like using a gun to kill immortal without taking their head, giving them time to run away.  Again, balance would be an issue here.  Beheadings should be somewhat rare and a bit costly even if you win...i.e. the quickening temporarily makes you weaker even as you get stronger in the long term.  

2.  I would want to pick from several different weapon styles but not individual moves from every style.  I would be trained in one melee weapon if I was an immortal and maybe pack a handgun but all of the cool stuff would be based on the melee weapon I chose.  For mortals, go ahead and let them have pistols and that but nothing miltiary grade.  If they want to use RPGs, hand grenades and that, I want them to break the law for buying and using such weapons.  Maybe NPC police would attack them and PCs could attack at will because they would be flagged as outlaws.

3.  Immortals can only gain so much power unless they fight other immortals.  The defeated immortal is removed from the server...I mean you can save the initial selections you made on style, looks, etc but you have to restart and rename your PC.  

4.  Money is important for obvious reasons but I don't want quests like find me X.    Ideally, I would prefer some sort of mystery or someone asks me to be their bodyguard.  I would also like to see some sort of virtual economy take place where having a job is possible and useful...getting money, helps with secret ID, etc.

5.  i would like to use mostly the orginal Highlander, definitely not Highlander 2...maybe the TV series as an expansion?

I wish I had time to post more things but I try to do so in the future.  Meanwhile, what would you want to see and how would handle running the game?

I would love to see an highlander mmorpg, the movies and tv serie were amazing. You are right, a lot of work would have to be done to balance the game, but on the other hand ,it could be amazing to have such strong characters.

I think the concept could be a bit like Jedis in star wars galaxies, but then again, i didn't play the game, i just heard that some very very strong characters with limited life were available for those who unlock them.

If you really think about it, the actual duels only take a very small part of the movies and the TV shows, even though they are some of the high points of the action/drama.  The secrecy and intrigue are like the cake to the fighting's sweet chocolate frosting.  The idea is rich enough to take place in any time period.  It might help to set it in a past era where you could justify battling and fighting a bit more.

A friend worked on an official-but-cancelled Highlander MMO for a while. He said that it was enjoyable as they got to fly to Paris frequently for long meetings with the license-holders.

I can see if I can prod him for more of the design, but one thing I remember was that they were talking about making content be based on historical periods rather than zones... like you'd begin in a starting area in the distant past, and as you leveled up, you'd move through time into more recent eras, until the modern world was the highest-level region.

I can't remember much more than that.

I would love to hear more about it.  I know you said it was cancelled but it would still be very interesting to hear about they were going to design it.