Europa Universalis IV: Developer diary 32 - The more the merrier!

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Johan's Home Account
Mar 14, 2001
Welcome to the 32nd Development Diary for Europa Universalis IV and this time we give you the juicy details about how to make the most fun aspect of the game more accessible to all players. And nothing is more fun than playing with your friends, and conquering their puny empires with mighty Ulm.

New Network Code
The old network code that served our games for many years has been discarded. We are now running on Steamworks, and this gives us some advantages. For example, this code supports NAT punchthrough, so you no longer need to open ports to be able to play with your friends.

One major complaint we've had about the multiplayer experience in our previous games, is the hassle with having to rehost if someone loses their connection or wants to join the game at a later time. We have rewritten our network kengine from scratch and, if the host so desires, players can join a game already in progress through what we call hotjoin. That player will then connect, and get the savegame sent to him or her, allowing that player to join with minimal work, and with just a small pause for the rest of the players.

Since we have changed our network code, this means we had to retire the use of the old metaserver. EU4 uses Steam’s hosting system, where you'll see games hosted, and you can chat with anyone else in the global EU4 lobby.

Through this lobby, you can invite one of your friends to join you the server you are already playing on or into your singelplayer game.

In the matchmaking lobby you can see what your friends are doing and, if they are playing EU4, you can ask to join their game.

If you like, you can choose to list your server on the public server list where everyone can find and join it. It is possible to add different meta data to the server, such as server name and tags, that are then searchable in the server list. It is also possible to password protect your server.

There are no technical differences between a singleplayer game, and a multiplayer game. So if you are playing a singleplayer game, you can easily turn on hot-join and allow your friends to join it. You know, once you built up a considerable lead.


Standalone Server
As is the case with all serious multiplayer games, EU4 comes with the option for standalone servers. This program allows you to run an instance of EU4 that is simply a server of game-mechanics with no graphical interface, or player playing on it.

This server can, of course, be configured to be password protected and whether it should be visible to the matchmaking servers or not. What makes it more flexible is that you can define who can play certain countries or if only a set of countries is available or not. You can set the names for your saved games and the frequency of the autosave from this file.

You can also set your server to boot up the lobby at a certain time, and then start at another time, and finally end at a certain other set time. When it reaches its endtime, the game will also be saved to the set filename. This allows you to schedule games with precision.

You can also set the start date for the game and give it permission to pause if there are no human players currently active in the game.

Our goal is to have a few servers running constantly for people to join in, to play a country for an hour or two, to have the fun and crazy experiences that multiplayer veterans have become familiar with.

Improved Chat
Eu4 has an improved chat compared to EU3. We are using the one we premiered for HoI3: Their Finest Hour, where you can have chat channels and secret whispers. It also has a long scrollback so you can see all the previous chat, and is easily minimized so it won’t obstruct the screen while playing. You can also clearly see when a private message sent to you.

AI Takeover.
As all who have played a game over the internet can testify, shit does happen. Sometimes you lose your internet connection, sometimes you lose power, sometimes the game even crashes. In EU3, the host could then decide to have your country either go braindead or become fully controlled by the AI. In EU4 we have expanded this, and now have a few options where you can tell the AI how they should govern the country while the human player is AWOL. You can tell it to avoid starting wars, to keep alliances even if an AI would cancel them, whether it canmove merchants or not and more customization options.

What is also cool is this aspect is saved in the save game file, so if you miss a session in your MP campaign, your country is more likely to be as you want it when you get back to playing it again.

Ps. And a small bonus - the Europa Universalis IV: Casus Belli Music Video with some new gameplay clips ;)


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Impressive! Well done Paradox.
Finally! These are nice additions!
I think it will be quite fun to just jump into a public game and play for a few hours, even if you plan to never return. Or, when you play, it could lead to a less lonely experience in your own game with people constantly jumping in and controlling the nations around you.
*Insert generic complaint about having to use Steam here*
Making AI force keeping aliances is good option.

If playing eu IV MP will be now like playing CIV IV MP, then it will be much easier to find someone to sub... Or even just make campaighn with player rotation...
I imagine some people might just drop into to a country in one of the full-time servers, declare war on everyone possible (Or something else annoying), and drop out leaving the AI to wreak havoc or be destroyed for no reason... I'm sure plenty of annoying things like this could happen. Other than that, it looks great, thanks paradox! :)
The only thing that was missing from my EU3 experience was multiplayer. This will open up a whole new world for me! Excited!
The only thing that was missing from my EU3 experience was multiplayer. This will open up a whole new world for me! Excited!
Exactly how I feel.