Building on top of existing works is a fundamental principle of creation, and one that has its place within precepts of intellectual property. But that idea increasingly seems to run up against a modern interpretation of IP law, and copyright in particular — specifically, the hyper-protective view that many well-heeled creators take in protecting their work. It goes beyond the product itself, particularly in the case of entertainment: don't even mention a film or show or any sort of product in a YouTube review, lest you risk having your videos flagged for infringement. It's IP law as aggressive, a tool of offense, rather than as a defensive measure against misuse, and that theory is being fought over in the courts on a regular basis.
In the latest skirmish, video game developer Rockstar has won a summary judgment in the UK against two of the five of the creators of a cheat dubbed "Epsilon" for the Rockstar-created "Grand Theft Auto V". (The other three settled.) For those not conversant in video games, a cheat is basically what the name suggests: a work-around to give characters items and abilities beyond what is standard, or to reshape the game in some way. The defendants' argument that the cheat came with a liability disclaimer and was developed using other pre-existing code did not sway the court in its ruling for Rockstar and its parent company Take-Two.
What did seem to resonate with the court was Rockstar's argument that in creating a cheat, the "Epsilon" developers were in some way violating copyright on the game in offering a version that differs from what the creator published and sold. As Timothy Geigner notes in Techdirt, that argument rests upon the idea that those plunking down $60 (or whatever the commensurate rate in British pounds) doesn't actually own the game they leave with, but rather licenses it. Thus the cheat developers are breaking the end-user licensing agreement and violating copyright.
Whatever you might think of the cheat itself, the Rockstar argument is absurd on the face of what we think of as common sense ideas of ownership and copyright law. The "Epsilon" creators are not offering a version of the game, but rather an ancillary product to those who have already purchased it. And while the Rockstar Games End User License Agreement offers wide latitude, that doesn't necessarily make the interpretation the correct one. In a more ideal system, copyright should protect against the loss of ownership and profit through infringement, but it shouldn't constitute the ability to control a product through the entirety of its lifespan. But this is the copyright world we currently live in, and we'll see more cases like this as companies get more aggressive in the courts.