What is genre?
Here’s my definition, pulled together from various sources: Genre is a set of expectations an audience has when approaching a form of media.
Until about eight years ago, I didn’t put whole lot of thought into genre and RPGs. Not many players do. They just pick what they want to play and play it.
At times I played or dabbled into other RPGs: Star Wars RPG, Mage: The Ascension, Warhammer Fantasy Role Play, Dark Heresy, and so on. GURPS spreads across multiple genres.
My default RPG was whatever current edition of D&D was on the market. I was never quite happy with with 3.5e, but I ran it. The “D20 System” pretty much covered every genre out there. Yet I wanted something more like AD&D 2e with the “feel” of first edition.
And then D&D 4th Edition came out.
Genre might be hard to define, but players know when their expectations aren’t met.
Imagine Call of the Cthulu without insanity. Imagine Star Wars without “The Force” or any Lord of the Rings RPG without Hobbits or Rangers?
What would happen if gamers bought an edition of D&D, expecting something more like AD&D 2e, but instead got World of Warcraft on the tabletop?
That’s D&D 4e. It didn’t meet player expectations.
For sometime I tried running D&D 3.5e in a “low magic/grimdark” setting. It didn’t work well after the characters reached about 5th level or so.
Game masters wanting to run primarily a deep roleplaying and storytelling campaign should shy away from rules-dense systems like Rolemaster.
Now I’m looking at running a low magic sword & sorcery sandbox campaign.
Two major candidates for this are Advanced Dungeons & Dragons and Dungeon Crawl Classics RPG. I’m leaning toward latter, because its basic rules resemble rules from modern iterations of D&D. Yet it encourages judges to maintain that sense of wonder.
When I say, “sword and sorcery,” prospective players will have idea of what to expect: lots of action, dangerous dungeons, evil cults, and lost ruins. When I say, “low magic,” players won’t be disappointed if there’s a not a “magic shop” or when I tell them to roll up 0-level characters.
The “sandbox” part might confuse some players who haven’t heard of the term before, but that’s easily explainable: exploration driven by the goals of the player characters.
You could argue that a GM should choose the genre before choosing the rules.
Yet if you plan on running a given set of rules, chances are you’ve already chosen the genre you’d like to run.