I've been doing a lot of thinking about what I might want to run as my "Hufflepuff" game, meaning the RPG that is open to a large number of players including several new and inexperienced ones. In full disclosure I've probably spent too much time ruminating about this instead of just running something, but I've got time and I don't want to botch it.
So obviously the first question is which game, or really which genre from which I can then select a game. I thought I would tackle each major genre separately, weighing pros and cons. First up? Fantasy.
The biggest upside to running a fantasy game is that it is the game everyone already owns. Or more specifically, 5th Edition Dungeons and Dragons is the game everyone already owns. I considered some other fantasy RPG's, like Fantasy AGE or Heroes Against Darkness, but teaching a new system or asking people to but a new rulebook would mean foregoing a big asset to running fantasy. Plus I'm not sure the benefits of a different system are all that great in the long run.
As a general rule, it is a system that accommodates large groups well. Fighters fight and wizards cast spells and clerics heal people and everyone feels like they have a job to do for the group. Sometime being a support role isn't as much fun as doling out huge amounts of damage, though.
In addition, I have lots of toys for running fantasy games. I've been building up two modular dungeons: one a classic style stone block dungeon and the other done in a natural cavern style. Plus there's loads of painted miniatures that I've been working on over the years, etc.
On the downside, I've been running a lot of fantasy lately. It was the last RPG I ran, and that campaign is still currently going on under another GM. Now that GM doesn't mind another fantasy campaign in the mix, but there's something to be said for offering something different, both in terms of my own creative "freshness" and not muddying the waters.
Conclusion: fantasy is a strong option, especially if I can do something a little different than what's been done before. It's not without its faults, however.