Notes From the Tavern Keeper - How I Run Convention Games (YMMV)
I've now run convention games (Swords & Wizardry Light to be exact) at NTRPG 2017 and Gary Con 2018 - two sessions at each convention. At North Texas it was all "theatre of the mind". At Gary Con we had a level of Rappan Athuk in 3d dungeon terrain. It was certainly a different experience between the two, but some things for me remained consistent. Below is how "I Roll." Some of this might be useful for other GMs to consider or not. The only hard and fast rule is "Have Fun"
I roll characters at the table. With SWL clocking in at 4 pages as well as having character class cheat sheets that double as character cards, character generation shouldn't take more than 15 to 20 minutes, even with a table of 10 or so. Heck, my players expecting a 5e game adjusted to SWL with no issues and character generation went just as smoothly.
Note, I allow surviving characters to be used in follow up sessions at later conventions, so yes, your characters can "level up." Not an original idea - +Matt Finch and +Bill Webb do the same. It does allow for a bit more buy in from your players than "one and done" games do.
Keep it moving. While your home game may consist of half an hour of catching up and banter at the beginning of the session and assorted bullshitting throughout, a convention game must fit into a particular time slot. Additionally, if the pace slows you will lose the attention of your players. For most games you want a thrill ride, not a plodding place.
I embrace walk ups to my table. Generally speaking, most games expect 6 to 8 players. With the Swords & Wizardry Light rules, I expect I can handle up to a dozen. Even if the game is started we can probably fit you in (note, I'm speaking for myself here and not others - games with pregens and such are much more difficult to add a random person to the game)
Project your voice. While this wasn't much of an issue at last year's NTRPG Con, as we had a semi-private gaming space, at Gary Con we were set up in a hallway right outside the door for the majority of the wargaming going on. The table was large and I had to project to be heard. I wasn't always successful but I tried my darnedest.
Minis are used best for marching order. Even with the 3d terrain, it was difficult (if not damn impossible) to accurately show battles and digging out appropriate monsters would have been time consuming AND would slowed down the pace. Moving minis from room to room also slowed down the pace. But using them for marching order and pointing out the location the PCs were in combined theatre of the mind with a 3d dungeon seemed to work best.
Make magic special. Magic items that are unique will be remember well after the players leave the session. They don't need to be over powered to be very useful.
When your players are about to go off the map, improvise. They find the secret entrance to a lower level? Have it lead to a hidden chamber.
Embrace the metagaming. Its going to happen, especially with 3d dungeon terrain revealing secret rooms and occasional traps (doors to nowhere) - "Yep, there are two doors in this room that go nowhere. Don't blame me for what happens ;)"
The bottom line is everyone should be having fun. If folks walk away happy and energized, you did well.
The Minotaur for Old-School Essentials
*Requirements:* Minimum STR 9, Minimum CON 9
*Prime Requisite:* STR and CON
*Hit Dice:* 1d10
*Maximum Level:* 8
*Armor:* Leather, including shield...