A normal campaign is one group of friends at one table, playing every week (or trying to). A West Marches game has one big pool of players instead, and every session is an adventure of its own. Whoever can make it on Tuesday plays on Tuesday.
West Marches was a campaign Ben Robbins ran for a little over two years, with one GM and a pool of about 10 to 14 players. The players did the scheduling. Someone would email the group with where they wanted to go and when, the players who were interested replied, and they worked out between them who went.
Every character was based in the same frontier town, and they could go anywhere except back east, to civilization. The wilderness out west was dangerous on purpose, and part of the game was learning when to turn back. (A march, by the way, is an old word for a border region, so the name means the western frontier.)
Games that use the name today have drifted a long way from the original. When someone asked on RPG Stack Exchange, the accepted answer said you can count on three things at the very least.
A few habits follow from that. Every adventure starts and ends at a shared home base, a bit like an adventurers' guild. The world persists, so what one group does can change things for the next. Players can bring a different character each time. And many games have several GMs, each running their own adventures in the same world. The original had only one.
The style spread online. Today the name covers almost any open table, meaning a group where players choose which adventures to join and which character to bring. On Discord, people play around their own schedules and time zones and still share one world.
The games I've played in ran on Discord, with Roll20, Owlbear Rodeo or just a voice channel for the play itself. Foundry VTT is popular too.
I've played in several, and my favorite part is dropping in. There's no weekly slot to protect. If I have a free evening I find an adventure and sign up, and if I'm busy, nobody's game falls apart. You also end up playing with people you'd never have met at a fixed table.
The hard part is the start. Every community has its own house rules, usually spread over spreadsheets, pinned messages and docs, and just finding them takes a while. Then there's the worry about doing something wrong, like breaking a rule you never saw.
For the GMs, there's a lot of work outside the sessions. Announce a session in chat and it gets buried under everything else, so players miss it. Characters play with different GMs, so their XP and loot end up in a spreadsheet that somebody has to keep up to date, often by hand. The GM also has to handle signups, player limits and level requirements. And every GM needs to know what changed in the world since they last ran something.
That's WestMarches.games, the site you're on. It's free, and it's made for West Marches communities that play on Discord. Unlike in Ben Robbins' game, the GMs post the adventures here, with player limits and level ranges, and players sign up. The bot posts each adventure and its recap to your server. The site keeps each character's XP, gold and rewards. You sign in with Discord, and your server roles decide who can do what.
The house rules I had trouble finding as a player have a place here too. The character creation guidelines sit at the top of the form every time a player creates or edits a character, and the rest of the rules can go on the world wiki, next to the setting.
D&D, Pathfinder and Daggerheart are among the 22 game systems you can pick, and any other system works too. It isn't a VTT or a character sheet, so keep the ones your group already uses. There are no ads. Some extras are Patreon features, which switch on when someone who supports the project on Patreon picks your community.
The history comes from Ben Robbins' Grand Experiments: West Marches on Ars Ludi. The rest of that series is on the Resources page.