ditto...except with running

I guess what I want is:

A well-defined background that creates plenty of opportunities for conflict of interest between different groups, and is flexible enough that people can create new and interesting characters. At the same time, an emphasis on group play is preferable for me as well.

It should also tell people what they can and cannot play, because I'm sick to death of people playing stupid ideas that don't fit into the world they're meant to be in even remotely. Someone may well have spent hundreds of pounds on a costume for manga convention, but Bubblegum Crisis doesn't fit into a swords-and-sorcery campaign. It would be cool in a cyberpunk campaign, but that's different.

A rules/mechanics system that tells me pretty succinctly what I can and cannot do, without me needing to refer to complex, difficult to remember rules, or having to enter into complicated or disruptive mechanics every time I use those rules. Having to shout a word each time I use a weapon or casta spell is absolutely the most disruptive thing I want to do.

That said, a skills system is necessary. An opportunity for progression would be ideal as well.

A downtime system. I used to think that this was pretty pointless, but now I think that they're cool.

I'd like to see a minimum costume standard at events I attend. It doesn't have to be much, because as long as you have one, people seem to try and out-do it by a long way. A good event has a standard (ie tunic and dark trousers, no white trainers), and if people are struggling to meet it,helps them out a bit (IE lends them a tabard or something). Setting minimum standards at, say, museum-quality replica costume would be just silly, though I've got no problem with people wearing that sort of thing.

Also, magic systems hould be simple to understand and phys-rep.

Ditto backgrounds. Ever group should have one, and refs should be given a copy. If a player doesn't fill one out, then they could be assumed to just fit into the group backstory somehow. Ideally, everyone should know how they ended up in the group. Their personal objectives can be set out this way.

I want to emphasise player-player interaction over the running of pre-written plotlines. It's OK to feed objectives to players, but I don't like that 'oh, so this time the uber baddie is THIS guy, and we need to find THIS to kill him, and...oh. An NPC just did it all for us.' Plotlines tend to degenerate into un-interactive events that players stop being participants to, and instead end up just observing.

A player-player game tends to develop all the elements in play that I want; physical and political conflict, treaty-making and deal-brokering, rumour-mongering and espionage.

In terms of people roleplaying skills; sure, it's great. I don't expect a surgeon to actually OOC know what he's doing, but I would prefer him to pretend; IE act like he's stitching me up etc in the open. If it's things like tactics that they're meant to be good at; well, sure in that case it'd be nice if he or she had a basic understanding of that kind of thing.

I've got plenty of time to drink beer and sleep the rest of my life. I don't care too much if the game is demanding; though ask me again in 10 years time! However, beer, mead and a good tune go down well whatever the event. In fact, one of the first things we ever try to do is write IC songs. I'm working on 'The Glory of New Mill-En' at the moment...otherwise, proper folk tunes are cool, like 'the Dead Man's Shilling' or 'the Bonny Black Hare'.

And finally, I think that Miriam's point is very important; IC grudges should be dropped once someone starts a new character. OOC grudges should not affect the game. If people can't manage that then they should stay at home. It's simple enough, and not everyone gets along all the time; fact of life. If it's really that bad , keep out of each other's way.