Firstly, sit down and have a chat with all of your players both individually and as a group about why you want to run the game. Tell them what excites you about it and how long you’ve been thinking about it. Most players will be sympathetic if there’s a game you’ve been yearning to run for years even if they have no personal interest in it.
Once they understand your enthusiasm, find out what they think about the game you’re offering and what kind of game they prefer. See if they’re willing to at least try the game and offer to let them play without having to learn any of the rules. Let them know some of the most useful techniques in that style of game so that they can feel confidant playing it. You want to set the entry barrier as low as you can.
Perhaps they would be happy to play the game but have a very specific concern. They might really enjoy character consistency and fear losing several characters a session or perhaps they really enjoy a violent solution but are happy to find it after a lengthy political or investigative adventure. Are there adventures you could run which could satisfy those requirements within your desired genre or game world?
There’s a chance they’re just not interested in a campaign that doesn’t excite them. That’s pretty normal. What if you ran a single adventure before returning to the usual fare? Naturally if you do this you must keep to your promise and not press for additional adventures unless your players are champing at the bit to continue. Put your fave game aside for awhile, at least six months, and then suggest another once off.
Presuming they’ve agreed to try the game, you shouldn’t penalise them too harshly for using old techniques or forgetting new ones. Yes, your players should be reasonable and not immediately try to gun down the vampire prince for being rude to them (presuming they know that’s not what the game is about) but is it really so bad if they breach the Masquerade here and there while trying out their cool new powers?
Compromise and be explicit in your compromises. Tell them that you’re willing to make the Masquerade more flexible but that you’re excited about them using underhanded techniques against the vampire prince. That way the players know which part of the game is important to you. After all, at this stage they’re only playing it as a favour to you.
Accept that the first game you run in that genre might not be what you’ve dreamed about. Those players who are used to narrativist Indie games might not think to declare that they’re looking for traps every time they enter a room in your dungeon crawl. Give them some reminders so that they know it’s something they are supposed to do. Introduce unfamiliar consequences with a light touch. Perhaps they see some charred adventurers who were careless a day ago and maybe the first trap they encounter only deals 1d3 damage.
Reward them for trying the new techniques they haven’t used in previous games. If they try to shadow the cultist, let them find something interesting even if they don’t end up at the villain’s HQ. If they flirt shamelessly to distract the security guard while another person tries to swipe the key card, let them get away with it. Sometimes videogame genre assumptions will trickle in and provide an easy point of reference for the characters in an unfamiliar RPG. If they want to crawl through a vent to infiltrate the enemy base, why not allow it this once in your techno-thriller? You can cleave closer to reality next time.
Hopefully if you do all of these things they will have enjoyed what you were itching to run and are willing to try another game with those rules or in that setting, if not now, than sometime in the future.
So what do you think? Let me know in the comments section if you have any other ideas on how to get players to try new games. Or on how to encourage the GM to try a new game (often a trickier prospect).