Every game that is primarily based on software could be considered a computer game. In general a development studio or software development company produces software. In the gaming sector this means especially computer games, including console games or arcade machine games. There are different kind of developer situations. Sometimes single persons develop computer games, sometimes dedicated companies develop their own games and bring it to the market, but today for the most part, games are developed for publishers. This means, a development studio is hired for creating a new computer game. This usually means, the publisher sets the goals of those project, how the game should be developed and what the details of the artwork should look like.
Here is an incomplete list of game development companies and some titles they are known for: