Malware in Games
Malware means software designed to function in ways that mistreat or harm the user. (This does not include accidental errors.)
Malware and nonfree software are two different issues. The difference between free software and nonfree software is in whether the users have control of the program or vice versa. It's not directly a question of what the program does when it runs. However, in practice nonfree software is often malware, because the developer's awareness that the users would be powerless to fix any malicious functionalities tempts the developer to impose some.
Here are examples of malware in games.
nVidia's proprietary GeForce Experience makes users identify themselves and then sends personal data about them to nVidia servers.
Modern gratis game cr…apps collect a wide range of data about their users and their users' friends and associates.
Even nastier, they do it through ad networks that merge the data collected by various cr…apps and sites made by different companies.
They use this data to manipulate people to buy things, and hunt for “whales” who can be led to spend a lot of money. They also use a back door to manipulate the game play for specific players.
While the article describes gratis games, games that cost money can use the same tactics.
Oculus Rift games now have DRM meant to prevent running them on other systems.
Some proprietary games lure children to spend their parents' money.
Angry Birds spies for companies, and the NSA takes advantage to spy through it too. Here's information on more spyware apps.