Slay the Spire and Monster Slayers are both roguelike deck-building video games in which players attempt to complete a series of dungeons comprised of distinct categories of encounters, including combat, merchants, occult rituals, and campfires. Both games allow the player to equip a few items to give enduring boosts to core stats. Both games allow the player to make constrained choices about which encounter to pursue next. In both games, combat is presented in a 2D, side-view with a hand of playable cards held in the foreground; playing cards prompts simple combat animation movements depending on which kind of card is played.
Slay the Spire released on Early Access in “late 2017,” with a full release in January 2019. Monster Slayers was initially released in March 2017.
I’ve spared a lot of other details of the overlap between these games. Is this copying? Plagiarism? An infringement of intellectual property?
Probably not, no—even though it’s genuinely difficult to describe these games in a way that makes them sound very distinct from one another.
So, how similar can two video games be before there is a problem?
I. The Purpose and Limits of Intellectual Property (in a paragraph or two)
The concept of genres, generally, presents challenges for intellectual property protection. In both the arts and the sciences, most people understand and accept that there are concepts, toolsets, and constraints that tend to push creative works towards certain points in the same way that the center of a galaxy holds the planets, stars, and cosmic dust in orbit. Debate rages around some points of overlap, some outliers, some fringe data points– but people nevertheless use terms for genres and categories as though these terms have meaning. Pop songs tend to sound similar to one another, but are usually recognized as distinct from jazz, classical, or metal. First-person shooters look and feel similar to one another, but are usually recognized as distinct from real-time strategy, puzzle, or fighting games.
Law is always an effort to balance competing claims. Sometimes those claims are brought by sentient parties. Sometimes those claims are brought by reason itself. Intellectual property law, generally, is an effort to help creators (of various stripes) realize gains from their efforts, but it is quickly obvious that there must be room for many creators. Different categories of intellectual property do this in different ways. Patent law (backed by cases like Mayo and Alice) prohibits ownership on the laws of nature. Trademark law recognizes that merely describing a good or service is a very weak basis for a trademark and therefore merits very weak protective power. Copyright law understands that art draws from a common area of tools, techniques, and cultural concepts that allow art to operate and function as a means of expression and communication. Copyright law uses the term “scenes-a-faire” to describe those elements of artistic expression which are so common or fundamental that to grant copyright protection to it would do meaningful harm to the capacity of future creators.
In considering computer programs, the Supreme Court recognized that the use of a menu in a computer program could not reasonably be subjected to copyright protection; it was just a foundational part of how users used programs. The Court didn’t call computer menus “scenes-a-fair” in this ruling, unfortunately—probably because computers were relatively new devices and also because “scenes-a-fair” is historically tied to ideas in literature. I don’t think anyone else would use “scene-a-fair” to describe ideas in video game development in 2020; I’m just ahead of my time, which is to say, I’m wrong until the rest of the world catches up to me.
Video games have an established history of dealing with similar products in a small market. Games that displayed the player character’s hands and gun in the foreground and focused primarily (or exclusively) on navigating a level and shooting enemies weren’t widely called “first-person shooters” for most of the 1990’s; we called them “Doom clones,” in reference to the singular, incredibly successful game that defined the style of the genre for that decade. There is current debate over whether to make a similar linguistic shift around the use of the adjective “MetroidVania” as a descriptor of… well, it’s a matter of debate just what it describes (but the term is a reference to two popular and successful games, Metroid and Castlevania).
Slay the Spire and Monster Slayers both draw on basic, well-established genres, tropes, themes, and mechanics that are extremely unlikely to be subject to copyright protection. If campfires, dungeons, level-breaks, repeated run-throughs, block cards, or turn-based strategy could be “owned,” it would very seriously hurt the ability of other game developers to make new games.
II. If This Doesn’t Cross The Line, Is There a Line to Cross?
So, if there is room in the genre of deck-building and rogue-likes for both Slay the Spire and Monster Slayers, is there still such a thing as copyright infringement? If these games aren’t too close, is there such a thing as too close?
The easiest way to identify infringement would be the art-assets themselves. Although the design layout and placement of the art assets is similar, the art style and the actual images are very different between the two games. There are also some meaningful differences between the mechanics of the two games (Monster Slayer allows for the permanent unlocking of benefits for future run-throughs, for example). Generally, the similarities between the two games can be accounted for by noting that both games rely heavily on well-established and understood features of games and the relevant genres. Two games can be very similar without infringing on one another if both games rely heavily on widely- recognized tropes and themes without significant addition, detraction, or transformation.
Something that copyright and trademark law have in common: your claim to legal protection is generally better when you’re more creative and original.