How many GMs is enough to run a Mega-Game?

Question

My two friends and I are going to spend quite a bit of time preparing a mega-game. It will be a weekend long gaming session with around 20 players, and the three of us as GMs. We are trying to figure out the best possible use of GM resources given the large number of players. Should we reach out for 'helpers' who aren't quite GMs but do some housekeeping tasks? If that option does not exist, what other methods could be used to keep the game running smoothly?

Good answers should pull from experience running large scale games with multiple GMs, and what techniques were used in managing so many players while keeping all of them engaged.

Answer 1

Since you've specified this as system agnostic this is really just a logistics problem that boils down to "How do 3 people manage 20 people?" So we'll focus on minimizing downtime and maximizing engagement with a minimum of effort. As far as background I've run multiple con events that involved 100+ people in rotating tables and recurring multi-day adventures.

Planning and Prep Work

Do as much of the work as possible before the event. I would strongly encourage pre-gen characters. That way you are prepared for all of their powers, spells, etc. On the GM side, have NPC stats, plot outlines, common tables, anything you'll want to reference as you go in a nice handy cheat sheet or binder. Ideally there would be 3 copies, one for each GM. Having pre-made maps, or avoiding the need for maps all together is also very good for these settings.

On the note of cheat sheets, if you have newer players, or are using a new system it is extremely helpful to have common rules on a one page sheet to give to every player.

Separate Areas

Trying to have all 20 people be involved in anything that involves regular skill checks, attacks ,etc will be both very hard to manage, and also very boring for the 15-19 people not actively involved in that check. Breaking your players into 3 manageable units will go a long way towards a smooth experience. This could be done by having 3 physical areas the players need to move between, 3 different squads they act in, or anything else that separates their action into smaller groups. It's important to let people flow from one section to the next and back again, so that you're running a mega game, not three games that just happen to be near each other.

Delegation of Tasks

With only three GM's you want to offload many of the normal book keeping tasks of the GM to the players. The biggest things are usually tracking initiative, drawing/using a map, and looking up any rules questions that come up. The less time the GM spends handling the books, the more time he can be driving the narration. There's almost always a player who isn't in the spot light right that second that can look something up or keep track of initiative.

Keep the Rules Simple

This is really a must-do with this many people, and one of the reasons I advocate GM made characters. Stopping a table of 4 players to look up an obscure rule is no fun. Stopping a table of 20 is miserable. It's nearly impossible to get everyone refocused. Ideally no rules issue should take you longer than 30 seconds to arbitrate. If you cannot readily find the rule, make one up from experience. Note, it's important to warn the players about this before hand. Make it clear that your goal is a fluid and exciting event, not a spreadsheet party.

Keep the Action Moving

This is one of the biggest pitfalls of a mega-game. When there are long lulls in the excitement and action people tend to zone out. Getting 20 people refocused and on task is a real pain. The best way of doing this is encouraging Player Empowerment. Encourage them to interact with one another in character without GM arbitration. If the spotlight is on someone else, they can easily be having a small interaction while still focusing on the major events. When you see someone starting to check out mentally, try and give them something to do.

Lastly, Focus on Fun

All of these things are there for one purpose, to ensure that everyone is having a good time. If it seems like a rule or plot point really isn't working for the group, throw it out!

TLDR - Prep Work, Sub-Groups, Delegate, Player Empowerment

Answer 2

The answer by Skiptron pretty much hits all the high points.

I'd like to add a couple of things to it though.

IRL Time Planning

Knowing that a break is coming will help prevent constant interruptions by players leaving the gaming area. It also gives the GM a chance to take a deep breath, gather their thoughts, and figure out what direction they are going to head next.

Make sure you plan on taking a short break every two hours or so. A good 10-15 minutes is enough time to make a critical phone call, use the bathroom, grab a snack, or just stretch. Try to pause on a cliffhanger if possible but don't stress over it.

Plan a longer break for food periodically. Depending on the venue it is a good idea to have the meals themselves planned or have a list of nearby options you can give the players.

Character Generation

Pre-gen Characters

Pros: You can tell part of your story int he character backgrounds. All the characters will fit the world you are running so you will not suffer a massively out of place character concept (I'm looking at you dual wielding drow rangers in sunlight). You can choose to not give the wizard the one spell that will completely bypass a cool encounter you have planned

Cons: That is a lot of work you have to do up front, especially for 20 players. You need to make more characters than players if you don't want someone to feel like they got "stuck" with the crappy one.

Player Built Characters

Pros: Get you better buy-in from the players themselves. Takes a lot of front-load work off the GM.

Cons: The under-powered, overpowered, and uninteresting character possibilities are endless.

If your willing to work closely with the players either one of these can work since you can mitigate the worst of the cons. It does require alot of player communication and time. To help deal with the communication issue during creation I would recommend a google doc for each character. Share it with all the GM's and the associated player.

Ignore Below - Left for reference, not needed by for answer after system tag was added

System Selection

I divide most gaming systems into one of three major categories. Generally speaking the less rules the easier it is to run for a large group of people. I am sure there are tons of examples I don't know about or forgot to list here, please forgive me in advance.

Rules Crunch

These games have alot of specific rules and rely heavily on tactical combat. Tends to require Minis, Maps, Chart Look-ups, Lots of Dice, and/or Lots of Roll Modifiers. Gear tends to be a major factor in these types of games and can get very nit picky in the differences. Character sheets tend to be complicated and require 2+ pages to fix all the information in a well laid out manner.

Examples include DnD 3.5e, DnD 4e, Pathfinder, Iron Kingdoms RPG, Almost any 70's or 80's game (like BattleTech)

Rules Lite

These games tend to be able to run mapless. Modifiers are generic in some way (Boost Die in EotE or Aspect in FATE) so they are easier to track. Character sheets tend to be less complicated and can fit on 1-2 pages easily. There is usually some mechanic for the players to drive the story which helps keep the characters involved.

Examples include DnD 5e, FATE, Edge of the Empire, Savage Worlds

Rule of Cool

These games are all about the narrative and the rules are just kinda tacked on to give a concrete way of resolving differences. Props are usually just that, props, and not required for game play. Character sheets are generally 1 page affairs and sometimes are only kept as a reference outside of where game play is taking place.

Examples include Storyteller System (World of Darkness) and the Dread RPG.