Well, *I* will have a big leather duster for my costu,e (Though I expect it will come off for periods, because the bugger is heavy. It's a belongs to a buddy who, thankfully, is Troll-sized, so it actually fits me.
But here, let me give you an example... We have folks who show up in full costume... Fake ears and tusks, a mohawk, leather jacket, pacepaint, the works. Or guys who wear full military kit with airsoft replica guns.
Then we have guys like Drew at Gen Con, who always does an interesting costume, but it's never his actual Shadowrun character (He had an interesting gargoyle costume one year, and a satyr costume the next).
Then we have the 7 Dwarves (Though only 3-4 of them usually make it to Gen Con and play in the scramble, on average). They all have Dwarf characters for Missions, named after the 7 dwarves in Snow White. Their costumes, however, are T-Shirts with their names on the back
And plenty of folks don't wear costumes at all.
We encourage costuming, we love it, and I try to take pictures to post and show off. There's also usually at least one prize for costumes. BUT.. No, it's not mandatory, and there will likely be plenty others there not in costume either. So don' sweat it. If you have something to throw together, awesome. Otherwise, we can manage. LARPing may be Live-Action, but's it's also still Role-PLaying.
Bull