I don't see any need to give out game benefits in exchange for putting up posters, first of all. If a player loves his MU* enough that he'd go through the trouble in the first place, having his OWN poster without having to pay for it, and promoting his MU* and bringing in more players should be reward enough.

I did that when I was playing another game - they had an awesome website poster that we could print out, so I did, and hung a few in the community college where I was taking some computer language courses. I never once thought to ask for payment in any kind, in-game or out. I just was excited about the game and wanted other people to know about it.

If you feel that your players need to be paid to thumbtack a piece of paper on the board in the supermarket, then perhaps you should ask yourself what's wrong with your MU*, hm?

<grin>

Having gotten that out of the way -

As far as I know, the only person responsible for tacking papers illegally is the person doing the tacking. If that person represents a company in any official capacity - whether as a listed volunteer or employee, the owner of the offended object (the door, for instance) might have some recourse, I guess. But I'm also guessing that's a civil matter, with the exception of covering up street signs, which is a criminal offense (at least here in the USA).

My advice:

1) Tell your players that they can have their very own glossy 3x5 foot poster in 4-color print of their favorite MU* if they'd be willing to place a few of them in the dorm's mess hall bulletin board, or in the local supermarket's bulletin board, or in the "public board" in the town hall (some town halls actually have one of those! )

2) Tell your players that you expect that they will behave appropriately and not give your game a bad rep as one that encourages illegal activities.

3) Tell your players that if they DO mess up and post illegally, they're SOL and you won't go to bat on their behalf.

4) Add a statement to that effect on your website, perhaps as an addendum to your Terms of Service or User Agreement.

5) If you really want to reward your players for helping you out in an OOC way, reward them OOCly. Offer them a discount on a tee-shirt, or add a sparkle-gel pen with your game's logo on it in the tube of rolled posters you send to them as your way of thanking them for their help.

6) Add an extra OOC incentive if they e-mail photo files of them standing in next to the poster in the location they placed it, and upload those pictures on a gallery page. Show everyone who views your website that you have players ALL OVER THE PLACE promoting your game. Bumper stickers are great for this too, especially if you get photos of cars with license plates showing all different states and countries. A possible reward might be one of those neato sparkle-gel pens (I just love those stupid things), or a mousepad, or a set of game-related custom temporary tattooes, or a discount on the fee to attend your game's next gathering.

Giving in-game incentives for out-of-game assistance just seems to cheapen the experience on both ends, as far as I'm concerned.

Yes, but is it legally enough to put a disclaimer in their that says something like "We take no responsibilities.... for you doing so."?

I honestly don't think that anyone not in the actual employ, whether as a listed volunteer or salaried employee, would cause an unrelated entity to be held legally responsible for his actions. There might be certain municipalities that have criteria to the contrary...

But from the criminal side of things, the person who tacks the poster up is the person who is held responsible for it. Not the company who owns the poster. If it were otherwise, then the printing company who printed the poster would also be responsible, as would the company that sold the printing company the ink, and so on and so forth.

Honestly, I don't think I'd worry about it. If it was someone getting drunk in a bar and committing a crime, THEN you'd have the issue of the bartender allowing the drunk to drive. But the laws around here are pretty specific. It's illegal for a bartender to serve someone who's already drunk. It isn't illegal for you to give someone some posters.

If the organization itself was responsible for the activities of people promoting it (be it via posters, signs, whatever), do you think radical organizations like MoveOn.org could even exist?

This is a non issue. You have absolutely nothing to fear.