Would I want to play? Yes and no
I'll pretty much echo my thoughts from the other thread, but I’ll expand on them a little more. While I love the idea, from the execution, I don't think that this would be a game that's up my (or my players') alley.
Are one on one duels conductive to a team based game? Combat can take a long time, especially when you're the univolved one. Unless you've got a small game, patient players, short combats or heavy RP, someone's going to end up bored.
I'm sure that this is handled in the rules (but I'm too lazy to look at the moment) but would the quickining end up creating a power discrepancy in the group? You know, one guy gets a kill ahead, so he's stronger, then as the strongest guy, is the best choice to do the next fight, making him stronger, making him the best choice for the next fight, etc.
"There can be only one." So kill everyone else in their sleep. Now, hopefully your players aren't big enough jerks to do this, but the setting is
so nice for this sort of betrayal.
Now, be careful about character generation. A computer hacker has no place in the operation, as does a conman (two guys that I'm thinking about playing at the moment). So make sure you help the players make plausable characters for that mission
and the rest of the game. There's little that sucks as much as being the competely wrong character for the game, for example, a physically weak and clumsy guy in a game where guys are trying to chop off your head.
The house has the potential to fall apart.
Here's some palces where me/my party would mess things up.
"Let's split up. Me and Carl'll take downstairs, you guys take upstairs."
"Hm... Let me thin- No. Let's stick together."
One immortal with a sword charging 3-8 armed and (hopefully) proficient people with guns isn't going to work quite so well. What if the PC's plan ahead and use gasmasks and gas grenades, then cover each other? If it works in a situation where the PC's should be kicking ass, it'll set a really bad precedent towards this Allen guy, which will only get worse when, post immortality I get ill when passing him. I know I'd assume he's evil and up to no good after an introduction like that.
And speaking of Allen, I'd hate the guy. Why? Because you like him. You spent a lot of time on him. You made him really cool. You gave him
Robin ****ing Hood's sword. And you had him slaughter the entire party, regardless of tactics and skill. Regardless of if you want it to look this way or not, it's going to seem like he's your favored DM character, and you’re showing him off. I wouldn’t want to know why he’s got Robin Hood’s sword. I won’t care who his mentor was, or where he’s from, or how he learned the ancient art of the striking crane, long thought to be lost. Every time he’s in the scene, I’m going to feel insignificant next to his finely honed brilliance (because he
is so damn cool). Whenever he’s around, I’ll feel like there’s nothing I can do except sit around and take what’s coming. And that’s a bad precedent to set.
Now here’s the funny part. This sounds like something I’d love. If someone asked me to play in a highlander game, I’d be excited to play in it. But the thing is that I know a lot about failed RP experiences, and this sounds a lot like what I’d do. In fact, it’s disturbingly like what I’d try. That’s why I can see it going badly.
You’ve said that you know your group, so hopefully they won’t have a lot of the problems my group would have with that situation. But be careful. The first few sessions of your game will set the tone for the rest of the campaign. Or at least that’s how it’s happened in every one of mine. Be sure you set up the tone you want from the start.
And, frankly, I might just tell them that it’s a Highlander based game, simply to avoid some of the pain. Getting killed isn’t a problem then. It’s a necessary story element to become immortal and get to go around kicking ass with a sword. And I’d gladly follow along with stuff I wouldn’t normally in order to do so. But mostly, this is a gut reaction to the fact that every time a DM’s kept something about the campaign’s premise secret, the game has suffered for it. For example: There was one post-apocalyptic game we played in where the DM refused to give us any background info on the world, or our characters, just told us to make someone with a useful skill set in the real world. We wound up with two medics (one military, the other a EMT), a conman, a mechanic, a thief, and a hacker. We woke up with amnesia and the first 4 sessions were spent wandering in the wilderness, and set a bleak, dreary, ‘the world hates us’ tone that stayed through the rest of the game (which has been going more than a year now). It wasn’t until recently when the DM stopped being surprised when we assumed everything was out to get us, was hostile, and that we were screwed and were only surviving because he didn’t want to kill us (as 10 days without food or water will do to people). With a little warning, someone would have played a woodsman/explorer and saved us a lot of trouble every time we had to hike through the wilderness.
Anyway, best of luck, and I hope to hear from you again, saying that the game is going wonderfully.