Most computer games in the 1980s and early 1990s were created in a group work. Especially the commercial high quality titles were created never by a single author but as a combination of graphics experts, musicians, programmers and marketing experts. What remains open is the reason why? Why was a group needed, why isn't it possible to create by a single person?
The answer isn't located outside the creation pipeline, it has to do with technical restrictions. The if computer hardware is slow and if support tools are missing the only way in handling the constraints is team work. Let me give an example, The Commodore 64 had a main memory of 64 kb of RAM. The only way in creating computer games was the assembly language unfurtunately, writing such programs needs a lot of time. If someone is doing so for 6 months, he has no time for creating the graphics and the sound as well. The only way to program the code and create the graphics is, that 2 and more people are working together.
Let us imagine a different sort of technology. Today the average PC has gigabyte of RAM and lots of tools are available. in addition, high level programming language like Python are available. There is no need to write the code in assembly language. Today it is possible that a single person writes down the source code, creates the graphics, invents the game design, provides the sound effects and uploads the resulting video to youtube. if the game is smaller one, a single person can do so in a weekend. There is no need for group working because better technology is available.
But what is about the quality? Would can we expect from a computer game programmed in python by a single developer? The interesting point is, that such a game has the same quality like the games in the 1980s. The only difference is, that less ressources are needed to create such a project.
Let me explain the situation from the other point of view. Group working is an indicator that a lot of resources are needed which can't be provided by a single person. Group working means, that a project will need so much time, and so much different knowledge that a larger amount of people has cooperate to create something. Group working is needed if technology is missing. this can be shown for many different domains like video games, book publishing, construction working or automotive assembly.
Perhaps it makes sense to explain who group working can be introduced to a modern video game. Suppose the idea is to create a mini game in python which has around 500 lines of code plus some low quality sprites. It is a normal jump'n'run game without any extras. Does it make sense to see this as a large scale group working project? It is a rhetorical question, because it is a typical one man programming effort. It is nothing else but a hello world demonstration of somebody who has discovered the pygame engine and likes to learn how to use it for creating a game. It is not possible and it doesn't make much sense to ask a group of people if they want to join this project. It would take more time to contact all the people than writing the small amount of codelines alone.
The typical situation in the now is, that a single person creates such a game, uploads the video into the internet, and then will read through the comments to get feedback from the end user. Such an interaction is not equal to group working but it is something else. Group working in the classical sense means, that before something was published lots of people have to interact.
Let me give a counter example. Suppose, the python language wasn't invented yet. The only computer available is a VIC20 which has to be programmed in assembly language. Under such a constraint the same project (a jump'n' run game) is much harder to realize. It is not possible for a single person in doing so. So the alternative is, either to work in a group or not creating the game at all.