I’ve played in three. One was a multi-table, multi-session run of the Annihilation War in Marvel Heroic. One was a multi-table Monsterhearts game where the tables were in different time periods. The third was a multi-table Apocalypse World event with a huge shared map we unlocked as we Adventured and explored.
The Marvel game was fucking epic, one of my favorite con games ever; the war was being fought on multiple fronts, so we’d start the sessions with a briefing/assignments and spend a few minutes figuring out who’d end up where. Then we ran the session and regrouped with 15 minutes left for in-character debrief and reporting. It worked really, really well because we had that common goal to hold us on task even as we went on very different missions.
The Monsterhearts game was an excellent session with great players, but there wasn’t a readily-discernible common plot thread, and characters could get whisked off to other tables mid-game as a result of hard moves. I get what was intended, but we all agreed very early this was an awkward and intrusive system and started to invest effort in playing around it. It did not work. (Part of the problem was that we were playing to uncover the mystery of what was causing these space-time distortions, and that wasn’t really fun in the end)
The AW sessions were a huge bummer for me because we got a couple of players who decided they wanted a different MC at another table, and bailed on our table to go across the desert leaving my PC literally tied to a cross by a cult. Bye, we’re bored here, good luck! The default was that PCs could traverse the terrain and end up at other tables. Cool idea in abstract, disastrous failure in execution.
My take-home from all this was that it works best when you have a strong common goal across the game, a meta-plot like fighting an invasion of cosmic-powred Negative Zone Bug-Warriors. (Or, y’know, Nazis)
A common scene to kick off sessions and a common scene to end them where you can have tables communicate with each other is great. Allowing characters to move between tables between sessions can work as long as there’s balance and you sincerely believe your GMs are roughly equal in terms of skill and pull will players. If you have a single obvious ‘rockstar’ that might introduce tension.
I strongly recommend against letting players swap or move between tables mid-session. I’ve only ever seen this be disruptive, as much fun as the idea of sowing a bit of chaos or doing a run-in might be for certain players. And if I played in something advertised as a tabletop wide-con that ‘turned into a mostly-LARP’ I’d feel furious and betrayed. The table is the first , best safety tool, and if you intend for an element of your session to be switching mid-stream to LARP you owe it to everyone involved to be SUPER clear about that in the event description.