But when that word poisons something that I actually value, like a conversation about being non-straight in society -- that's when I'm not so sure about this.
"Gay" describes non-transgendered gay men, I don't think you can use it as a blanket term and I personally almost never use it that way. It doesn't describe lesbians. It doesn't describe transgender people. It doesn't describe bisexual or queer people. The worst part of Gay Pride is its name; it excludes those who do not identify as gay. It sucks to be excluded.
So here's the branding dilemma: do you exclude huge swaths of a community so you can make a really facile pun on a quaint / irrelevant marketing gimmick that has no currency along the frontiers of game design... or do you name your game convention something else?
Wait, I lied. It's not really a dilemma.
I'm not saying to name it "Queercon" or "LGBTQcon" because those names are clearly awful. I'm saying to name it something else. Be creative. There are these things called allusions and metaphors which writers (and marketers) have been known to employ sometimes. Maybe this is one of those times. I'm told unicorns are quite popular.
Anyway, good luck, Gaymercon. I know a lot of people who won't be attending you or speaking at you because of your name, which is really unfortunate. Some of them are quite famous and live, like 20 minutes away.
(And if someone asks why there's no "Straightcon" then tell them there actually is. It's called PAX, PAX East, GDC, E3, TGS, Gamescom, Eurogamer Expo, Comicon, Blizzcon...)