The game
Kingmakers co-op and multiplayer
Kingmakers multiplayer is co-op: up to 4 players online, through the entire campaign, with each player leading an army of their own. It is online only, so there is no split screen, but you can play solo without a connection. There is no PvP planned for Early Access.
The short answers
PlayersUp to 4: you and three friends
Online or localOnline only
Split screenNo; co-op is online only
Solo offlineYes, solo does not need a connection
Join mid-gameDrop-in, drop-out through the whole campaign
ArmiesEach player commands their own
VehiclesNot shared between players, as first planned
PvPNot planned for Early Access; maybe later
Crossplay (Steam and Epic)Not announced; named only as work extra stores would add
How many players
4players at most, online
4 armiesone for each player
Whole campaigndrop-in, drop-out from start to finish
“4 players total can play together, so you and 3 friends!”
Official FAQ. From the Kingmakers Official FAQ (Steam discussions)
“We’ve designed Kingmakers to be a great single-player experience. But the entire campaign is playable in drop-in, drop-out four-player co-op.”
Redemption Road. Said in the tinyBuildGAMES video: Kingmakers - Gameplay Deep Dive
Everyone brings an army
Co-op here is not four players sharing one force. The Deep Dive says each player commands their own, and the Epic store page describes it the same way:
“Up to three friends can lead their own armies alongside yours, and join in on your conquest in online co-op.”
Epic Games Store page. From the Kingmakers Epic Games Store page
Those armies fight alongside yours, for the same Welsh rebellion; the sides are set out on Kingmakers factions. The recruits those armies are built from are on Kingmakers units and officers. One early limitation from the developer blog: players would not share vehicles at first, each getting their own.
Drop-in with strangers, and what carries over
Asked to open matchmaking up to randoms rather than only friends, the director confirmed the game already works that way, with one caveat about players joining at very different power levels:
“Kingmakers is drop in/drop out multiplayer and is not invite only.”
“A significant amount of powerscaling happens in mission, and this is something we are aware of. We don’t plan to let someone roll in with a tank and just kill the mission.”
In the same thread he set out what a player keeps after a session with randoms ends:
“Yes, you will gain the same meta progression for your character whether you are playing online with randos, solo, or online with friends. The campaign progression itself is tied to the save file of that campaign though, but everyone who is connected to the server gets a copy of the save file that they can then continue to play solo or with other people/their friends.”
So a character’s own progress carries between solo, friends and randoms, and each player who was in a session keeps a copy of that campaign’s save to continue on their own. What that progression unlocks is on Kingmakers units and officers.
Split screen, local co-op and offline play
Together
Online only
“No, co-op mode will be online only.”
Official FAQ. From the Kingmakers Official FAQ (Steam discussions)
Alone
Works offline
“Yes, you will not require an online connection to play solo.”
Official FAQ. From the Kingmakers Official FAQ (Steam discussions)
So playing together in one room still means one PC each, and a solo campaign works offline. The campaign screen has an Invite Friends button of its own, pictured on the Kingmakers campaign map. The planned demo is also described as fully multiplayer; see the Kingmakers demo.
Solo, private lobbies and local co-op
Playing alone is the other half of the design, covered on is Kingmakers single-player.
A player worried that a good game would still force them to play with strangers and rule out a private lobby. The game director answered:
“You can play in singleplayer. You can have a private lobby and invite just your friends.”
“Why would we force you to play with other people if you don’t want to? We aren’t going to do that. Private lobbies already exist in the current builds.”
Asked whether local co-op is a must, he said it was not being targeted when he answered:
“yeah, we aren’t targeting local co-op currently. It is a really cool feature though which we included in Road Redemption.”
“We may add local co-op down the road.”
That agrees with the FAQ’s flat “online only” above, while leaving the door open. Neither reply gives a time. Asked again a week later, in the drop-in/drop-out thread above, his answer was shorter:
“Of course there are private lobbies. We aren’t insane.”
PvP
“It’s not in the plans for Early Access release, but we may consider it later for our roadmap if it’s highly requested.”
Official FAQ. From the Kingmakers Official FAQ (Steam discussions)
A later developer blog listed “maybe even a PvP mode” among things wanted after Early Access. That is the whole record.
Crossplay
Not announced, for or against. It has come up once in the game director’s replies, and only sideways: asked whether the game would be sold on GOG, he listed crossplay among the work every extra storefront adds.
“GoG isn’t ruled out or anything. For EA it isn’t targeted right now though because getting on additional storefronts is actually a significant amount of work in terms of supporting crossplay/achievements/etc, and we are focused on getting to EA as soon as we can.”
That says crossplay is part of the cost of selling in more places. It does not say whether Steam and Epic players will be able to play together. No plan for crossplay with PS5 or Xbox has been announced either; the console plans are on Kingmakers on consoles, and the store-by-store picture is on Kingmakers crossplay.