The Winter Meetings game, but later in the offseason. You can read a more detailed explanation here, but the gist is this:

• The game will take place from Monday, February 5 until Friday, February 9.

• All 30 subs will be involved in the game.

• Users can sign up as players here. General Managers (one or more per team, based on the amount of players on that team, appointed based on sub affiliation, previous experience, and reddit activity) here, or Player Agents (5 spots) here. You may sign up as a player and GM, but not as player and agent. If you do get chosen as an agent, you will be removed from the player list. Agents, GMs, and free agents will be announced on February 3.

• Contracts: All trades and free agent signings, unless stated otherwise, will be for the duration of spring training.]

• Beat Reporters: Beat reporters have access to the super-duper secret negotiating sub (/r/BaseballTradeDeadline), so they can break news of potential trades wellbefore the deal is close to finished.

Here’s a thing to keep in mind about the reporters. The less detailed the report, the less is really confirmed about the report, the more fun it is for everyone involved. Simply copying and pasting the latest trade that’s been negotiated before we have a chance to post it in the trade thread is pretty boring and doesn’t add a whole lot to the game. This is not to say that beat reporters should invent things, but. It’s sometimes pretty funny when they do.

Again, if this sounds like something you’d be interested in doing, you can sign up to be a beat reporter here. (Paragraph stolen without permission from this year’s trade deadline game

You don't have to participate, but the game is a lot of fun, even just looking at the megathread as the madness plays out.

Right now /r/SFGiants has more people signed up. As a subreddit I know we can do better. :)