Design, Development, Multiplayer, Network, Video Games , , , , ,

System Design for Multiplayer Games

Designing a multiplayer game might not seem like something that would require a lot of extra thinking compared to a single player game, and that might be true for some specific scenarios, but in most cases you start designing and suddenly you realize that things are getting a little out of hand.  When you’re finally grasping a general idea of how you want to design certain aspects of the game, you bump into one or two “What Ifs” from which you branch out into a complex spiderweb of design decisions. Before you know it you’re way over your head, confused, lost, and overwhelmed, then you think about all the hours of effort that you might need to put into your game just to get a Minimum Viable Product (MVP) running.

Well that’s what we’re here for, to talk about all these little and sometimes big things that affect our games and how we design them.

This is the first post of a series of articles that talk about the Design of a Multiplayer Game from a technological point of view. This article is aimed for Indie developers who have a desire to create a multiplayer game. I do not intend to tell you how to design your game but to guide you on how to make some design decisions and overcome some bumps in the road you may encounter while developing a multiplayer game. I’ll be highlighting some caveats, listing some common types of multiplayer games, and the work required to get them running. Hopefully this will ease your path into this challenging but exciting experience.

When talking about multiplayer games, we have a few options: Couch-coop, split screen, LAN, and Online games.  This series will regard only LAN and Online games, games that have a network component into them.

In this first article I’ll start by listing limitations, scenarios related to those limitations, and possible solutions for each. Each of the following articles will try to address the former in detail.

Lets get started.

 

 – LAG
I wasn’t sure if I wanted to start with this point or not, due to its complexity and all the things that need to be taken into account while designing a game that might be highly affected by LAG. And yes, some games are more prone to feeling “Weird” or just not working as expected due to LAG. This can be easily overlooked while designing a multiplayer game. Trust me when I tell you, LAG is REAL!

We will look into what are the differences between a Fully Authoritative server vs a more permissive approach. What if your game is Online or you just want to make a LAN game, “a la Counter Strike” when it first started, and possibly sell it as a product. What is Client prediction? What types of solutions are there? What are the Pros n Cons for each of these? What about Lag Spikes? Finally, we will talk about regional servers, and how this affects the game performance and your wallet.

 

 – Price/Cost
Regional servers could really hurt your operational costs. The fact is that all the points we’ve listed so far affect your OPEX somehow. You need to decide between selling your game as a product or as a service.  Those that sell their game as a service include any typical MOBA, Free2Play (F2P) or even an MMO like WoW. We will list and explain the necessary components to develop a game for each of these models. Moreover, we’ll talk about the scale you could start with. It is not only easier but also cheaper to grow something than to shrink down on your Cloud Structure.

What about your Content Distribution Network (CDN)? It is expensive to distribute your game, since there are storage and Bandwidth costs.
One key word is Cloud! Yes, most scenarios should use the cloud, because it’s not too expensive and will give you a lot of flexibility.

 

 – Server Types
What are the differences between having a dedicated socket server vs accessing a REST API? Where should I use each? Things to keep in mind while developing these.

 

 – The Networking Back-End
We’ll be talking about 2 engines in general, Unity and Unreal Engine. Both have a built-in Networking solution. Although these options are great for testing and making a quick draft, you can also create your own networking back-end solution which you’ll have total control over and can allow you to improve a lot on Networking performance, by controlling the size and occurrence of the messages and other cool tricks.

 

 – Game Modes
This is not related to what kind of networking solution you should use, this design decision is more related to how many people play the game and the sad but true possible scenario “What if there are not enough users playing my game?”.  What type of game mode should you start with? A free for all is always a good idea. What about queue times if you have a MOBA type of game? Should you do it match based or have big persistent maps?

These are some considerations to keep in mind while designing your game. We will discuss this in a top-down approach since these considerations come after the type of game you’re developing and not the other way around.

 

 – Multiple Services
There are some development choices that you might be forced to take because of some bottlenecks on some of the services developed. This will allow you to design ahead and have a clear view of what you need to do instead of having to re-factor your whole system in order to accommodate possible expansion scenarios. In short, if you do it right, you’ll do it once and it’ll be clear. We will go a little more into some topics like… What about friends, parties, chat, should I have my own VoIP? How will inter-server communication work?

In any case, we will try to approach most of the possible problems found in designing and developing a multiplayer game. I hope you find these articles useful.

 

After discussing all the parts that I want to point out that are necessary to understand and complete a multiplayer game, I will give some fully detailed examples on some game types such as: MOBA, FPS, RTS, and maybe even an MMO. I could also include some Mobile API based game. This will depend on whatever people requests I get.

 

On a side note: The reason why I say “WE” is because I include you into the discussion and expansion of these topics. It would be great if you can either comment or send me a message about the article regarding its content and  any concerns and specific question you may have. Your feedback will aid in enriching the articles posted here and allow us to further explore solutions for issues that may arise.

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