“Session 0” refers to a long and noble tradition of having a dedicated pre-game meeting to create characters and go over any homebrew rules. This is the time when you come up with character concepts, figure out how the party knows each other, and get the basic lore layout from the DM. The goal is to walk away with everything fitting together nicely for the first actual play session.
The “Session 0 Talk” is the sometimes awkward moment when everyone talks about what they want to get out of the game. Do they want a tactically intense combat campaign? Are they looking for cityscape intrigue? Due to the high likelihood of conflicts and weak conflict-resolution skills of many nerds, this talk often gets skipped.
The point of the Session 0 Talk is to get everyone on the same page. It lets the DM know what to prepare. It tells the players what kinds of characters might be successful in the type of story that’s going to be run. Nobody goes in expecting a combat-heavy campaign, geared up to the min/max of a lifetime, only to find out that 90% of gameplay will be skill challenges and roleplay. When you skip this, you virtually guarantee that somebody will have a bad time.
The answers in the above list are examples. The actual spectrum of possible valid answers is far too vast to guess at. You’ll have to actually talk about it.
This may seem like a lot of upfront work but you can imagine how having different ideas on any one of these will lead to fundamental conflicts within the group. It’s worth the effort. Everyone will have a better time if you set off on the same foot. Be upfront about as many topics as you can. Going in with the same expectations is absolutely crucial.
“Forbidden topics” is easily the most awkward part of this discussion. Talk to your group about topics you just do not want to play a story about. You don’t need to give reasons.
Imagine a person has a dog and just doesn’t want to spend their free time thinking about their dog being dead. A game about dead dogs is not going to work for this person.
There’s a huge range of triggers and preferences. When it comes to something as intimate as roleplaying, you really do need to speak up and tell folks what’s out-of-bounds for you.
Unexpectedly, the most common forbidden topic I’ve run into has been religious content. Folks either aren’t interested or have conflicts with “false gods”. These people are your real friends. Don’t push them for a reason and don’t shame them for whatever their topics might be.
Simple preferences are also important to get out of the way at this stage. If you’re not into modern slice-of-life anime settings, let the group know. If scifi is not your thing, the DM shouldn’t write a campaign about aliens invading Midgard (this time). If a group is unable to mix, it’s far better to find out here than 3 sessions in.
Part of these roleplaying games is modifying the rules as needed throughout the campaign. It’s very unlikely that you’ll be able to list off every homebrew rule up front. You should still make your best effort.
The DM should have a written list of any homebrew rules he’s definitely implementing. This could be special setting changes to races or how some rolls are handled. It could be a new currency system. Whatever it is, it should be stated before character creation – if at all possible.
The players should also be vocal about anything they’d like to try to homebrew in. Perhaps one fellow wants a turtle mount or another wants a utility belt that grants some bonus. Figure that all out during character creation. You can always modify homebrew rules later but starting from a strong and consistent foundation is best.
It’s boring admin work but it pays off immediately. Go over concepts so that everyone has a shared understanding of them. Talk about what “roleplaying” is and isn’t. Talk about whether an “attack” is a basic attack or anything requiring an attack roll. Discuss what you mean by “PvP” and “min/max”. The DM should initiate all examples and topics to prevent potential character spoilers. A player asking “Are we cool with betrayals?” kind of tips his hand.
The Session 0 Talk doesn’t need to be some big thing. You can cover most of these topics while doing other things or over lunch. The whole point is to keep the group together and make sure everyone has a good time. Talking about these things upfront will prevent frustrations and falling out later.
Note : Do not take a vote on each topic. Discuss each thing in a qualitative manner as a group. All voting will do is ensure one guy is feeling trampled on. You may very well find that your group is not well-suited to each other. In this case, I urge you to find something else to do together. Forcing a poorly-fitted group is a recipe for disaster.