It’s How You Play the Game: Why Videogame Rules Are Not Expression Protected by Copyright Law

Vol. 7 No. 4


Sonali D. Maitra is a partner at Durie Tangri LLP in San Francisco, California. She specializes in litigation—including IP and videogame litigation.

Most—if not all—courts apply the following test in determining whether a video game infringes another’s copyright: whether two games have the same “idea” only (which means no infringement) or something more in common (possible infringement). I argue that such analysis, while necessary, is not enough. In analyzing copyright infringement of video games, courts must implement an additional analysis that gives no weight to similarities between the rules and mechanics of games—regardless of whether such elements are part of a game’s idea. This analysis requires courts to determine, at the outset, not only what constitutes the idea of a game but also what the game’s rules are—and apply a consistent and coherent definition of what game rules are in the first place.

Game Rules Are Not Copyrightable

Section 102(b) of the Copyright Act states: “In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.”1 In using the word “or,” the statute lists these exclusions—ideas, procedures, processes, systems, methods of operation, concepts, principles, or discoveries—disjunctively. Thus, each has independent force and effect. This means that neither ideas nor functional elements—such as procedures, processes, systems, or methods of operation—are copyrightable.

The legislative history of § 102(b) is consistent with the understanding that neither ideas nor functional elements are copyrightable. In 1964, the register of copyrights proposed a revision to the copyright laws to define the scope of copyrightable subject matter: “Copyright protection subsists . . . in original works of authorship fixed in any tangible medium of expression, now known or later developed, from which they can be perceived, reproduced, or otherwise communicated, either directly or with the aid of a machine or device.”2 This language exists today in § 102(a) of the Copyright Act.

The stated proposal, on its face, brought within reach computer programs, and there was concern that this would bring within the scope of copyright “functional items.”3 A new copyright bill was then introduced, clarifying that copyright would protect neither functional items nor abstract ideas. This bill kept the above language regarding the scope of copyright protection, but further included a set of exclusions: abstractions (ideas, concepts, discoveries, and principles) and more complex functional features (procedures, processes, systems, methods of operation).4 This set of exclusions is now incorporated in § 102(b).

Congress explained the inclusion of § 102(b) as follows:

Some concern has been expressed lest copyright in computer programs should extend to the methodology or processes adopted by the programmer, rather than merely to the “writing” expressing his ideas. Section 102(b) is intended, among other things, to make clear that the expression adopted by the programmer is the copyrightable element in a computer program, and that the actual processes or methods embodied in the program are not within the scope of copyright law.5

In the context of games, § 102(b) means that rules, game mechanics, and any other functional elements—in addition to the overall idea—of a game are not copyrightable. The Copyright Office factsheet on games explains exactly this:

Copyright does not protect the idea for game, its name or title, or the method or methods for playing it. Nor does copyright protect any idea, system, method, device, or trademark material involved in developing, merchandising, or playing a game. Once a game has been made public, nothing in the copyright law prevents others from developing another game based on similar principles. Copyright protects only the particular manner of an author’s expression in literary, artistic, or musical form.6

This is consistent with early cases, which held that game rules and the overall systems created by game rules were uncopyrightable. For example, in Affiliated Enterprises, Inc. v. Gruber, the First Circuit held that the rules and overall system for a lottery game “Bank Night” could not be copyrighted, reasoning: “However good and valuable an idea, plan, scheme, or system is, the moment it is disclosed to the public without the protection of a patent, it becomes public property[.]”7 There are a litany of cases that followed suit, such as Whist Club v. Foster, which explained: “In the conventional laws or rules of a game, as distinguished from the forms or modes of expression in which they may be stated, there can be no literary property susceptible of copyright.”8

As explained in detail in the next section, cases involving accused infringement of a video game display apply a test to determine what the abstract, unprotectable idea of the game is as opposed to the copyrightable expression of that idea. The court abstracts the copyrighted work to determine the underlying idea of the work as distinguished from its expression, and compares the protectable portion of the work to the accused work to determine infringement. If the idea of the work is indistinguishable from the expression—i.e., “merged” such that there are a limited number of ways of expressing the idea—then copyright will protect against only identical copying. This analysis is perfectly appropriate when determining the underlying uncopyrightable idea of the work. But it is inapposite when determining the uncopyrightable functionality (i.e., rules) of the game.

In Lotus Development Corp. v. Borland International, Inc., Borland wrote its own spreadsheet program, but included in its computer programs a virtually identical copy of the menu command structure—including the specific words and arrangement of the structure—contained in Lotus’s competing spreadsheet program.9 The First Circuit found that the menu command structure was an uncopyrightable “method of operation,” as listed in § 102(b).10 It explained:

Accepting the district court’s finding that the Lotus developers made some expressive choices in choosing and arranging the Lotus command terms, we nonetheless hold that the expression is not copyrightable because it is part of Lotus 1-2-3’s “method of operation.” We do not think that “methods of operation” are limited to abstractions; rather they are the means by which a user operates something. . . .

The fact that Lotus developers could have designed the Lotus menu command hierarchy differently is immaterial to the question of whether it is a “method of operation.” In other words, our initial inquiry is not whether the Lotus menu command hierarchy incorporates any expression. Rather, our initial inquiry is whether the Lotus menu command hierarchy is a “method of operation.”11

The court found irrelevant that there were many different ways of implementing the menu command hierarchies, explaining that “it still functions as a method for operating the computer and as such is uncopyrightable.”12 The Supreme Court affirmed.13

The Borland court similarly refused to apply an abstraction analysis to the elements of Lotus’s copyrighted work: “We think that abstracting menu command hierarchies down to their individual word and menu levels and then filtering idea from expression at that stage . . . obscures the more fundamental question of whether a menu command hierarchy can be copyrighted at all.”14 As in Borland, the fundamental question here is not at what level of abstraction a game’s rules must be compared, but whether a game’s rules can be copyrighted at all.

Video Game Case Law

When video game cases implement an idea/expression analysis only, this analysis sometimes does, but sometimes doesn’t, account for similarities in game rules and mechanics.

Centipede vs. War of the Bugs (1981)

In Atari, Inc. v. Armenia, Ltd., one of the earliest cases to examine copyright infringement of video games, the Northern District of Illinois examined whether War of the Bugs infringed Atari’s Centipede.15 The court reached a preliminary determination of infringement in an “I-know-it-when-I-see-it analysis.” It explained: “The worms travel in the same manner. The shots were fired in the same manner. The [whole] arrangement was very similar.”16 There was no attempt to determine the uncopyrightable idea of the game, much less the uncopyrightable rules.

Asteroids vs. Meteors (1981)

In Atari, Inc. v. Amusement World, Inc., the court found no infringement of the audiovisual display of Atari’s Asteroids by that of Amusement World’s Meteors.17 The court, for the first time in the context of a video game case, applied the idea/expression dichotomy to determine which aspects of the copyrighted game were part of the uncopyrightable idea of the game. The court explained that “while one’s expression of an idea is copyrightable, the underlying idea one uses is not.”18 It further explained that “forms of expression that are essential to the idea (i.e., forms of expression which cannot be varied without altering the idea)” are also uncopyrightable.19 The 22 similarities between the two games (e.g., when a spaceship’s projectiles hit a rock or another ship, the latter is destroyed immediately) were “inevitable, given the requirements of the idea of a game involving a spaceship combatting space rocks and given the medium of a video game,” whereas the nine differences were expressive (e.g., the Meteors spaceship fires faster and continuously, while the Asteroids spaceship can fire only bursts of projectiles).20

PAC-MAN vs. K.C. Munchkin (1982)

In Atari, Inc. v. North American Philips Consumer Electronics Corp., the Seventh Circuit examined whether the video game K.C. Munchkin infringed the famous game PAC-MAN.21 Here, too, the court applied the idea/expression dichotomy but seemed to conflate the idea with the games rules: “In applying the abstractions test, we find that plaintiffs’ game can be described accurately in fairly abstract terms, much in the same way as one would articulate the rules to such a game.”22 It then described an idea as such an abstraction:

PAC-MAN is a maze-chase game in which the player scores points by guiding a central figure through various passageways of a maze and at the same time avoiding collision with certain opponents or pursuit figures which move independently about the maze. Under certain conditions, the central figure may temporarily become empowered to chase and overtake the opponents, thereby scoring bonus points.23

The court further held uncopyrightable the maze and scoring table, the “wrap around” concept, and the use of dots to gauge and reward players—all “standard game devices” and common video game tropes. It found infringement based on the following elements, which it determined to be expressive:

Rather, it is the substantial appropriation of the PAC-MAN characters that requires reversal of the district court. The expression of the central figure as a “gobbler” and the pursuit figures as “ghost monsters” distinguishes PAC-MAN from conceptually similar video games. . . . PAC-MAN’s particular artistic interpretation of the game was designed to create a certain impression which would appeal to a nonviolent player personality. The game as such, however, does not dictate the use of a “gobbler” and “ghost monsters.”24

Karate Champ vs. World Karate Champ (1988)

In Data East USA, Inc. v. Epyx, Inc., Data East accused Epyx’s World Karate Champ of infringing its game, Karate Champ.25 There were 15 features in common between the two games—most of which were karate game moves.26 Applying the idea/expression dichotomy, the court held these features to be unprotectable, reasoning that they were “game procedure, common karate moves, the idea of the background scenes, a time element, a referee, computer graphics, and bonus points, [that] result[ed] from either constraints inherent in the sport of karate or computer restraints.”27 Once those similarities in function were removed, the court found no infringement.

Over the next several years, a number of courts followed suit, applying the idea/expression dichotomy to determine the uncopyrightable aspects of the games to be filtered from the similarity analysis.

Golden Tee vs. PGA Tour Golf (2005)

In Incredible Technologies, Inc. v. Virtual Technologies, Inc., the Seventh Circuit examined whether PGA Tour Golf infringed Golden Tee.28 The court opened its analysis of the two games by explaining, “[C]opyright protection does not extend to any ‘method of operation . . . regardless of the form in which it is described, explained, illustrated, or embodied in such work.’ 17 U.S.C. § 102(b).”29 Citing Borland, the court concluded that “[e]ven if there are multiple methods by which an operation can be performed, a plaintiff’s choice of a particular method of operation is not eligible for protection.”30 It further explained that “[u]seful articles and functional elements” are not entitled to copyright protection, and invoked the patent/copyright distinction as the underlying policy consideration for this rule: “The exclusion of functional features from copyright protection grows out of the tension between copyright and patent laws. Functional features are generally within the domain of the patent laws.”31

The Incredible Technologies court concluded that the layout of the controls—while similar in the two games—was functional in nature:

To a large degree, the layout of the controls seems to have been dictated by functional considerations. The trackball almost necessarily must be in the center of the control panel so that right – and left-handed players can use it equally well. It must not be so close to the upright video display that a player would smash her hand into the screen too forcefully after making a shot. . . . We do not find an abuse of discretion in the district court’s conclusions that the buttons appear to have been placed where they are for purposes of convenience and cannot be said to be expressive.32

It similarly held uncopyrightable a number of other elements the games had in common as “inherent either in the idea of video golf or . . . common to the creation of coin-operated video games in general.”33

Tetris vs. Mino (2012)

In Tetris Holding, LLC v. Xio Interactive, Inc., the Tetris Company complained that Mino infringed Tetris.34 Although the distinction between ideas and rules was briefed extensively before the court,35 and although the court acknowledged that rules per se were not copyrightable, the court nonetheless conflated both rules and ideas and applied the idea/expression dichotomy only. But in defining the idea behind Tetris, the court was fairly specific, and noted that “the idea of a game is expressed, in part, through its rules”:

Tetris is a puzzle game where a user manipulates pieces composed of square blocks, each made into a different geometric shape, that fall from the top of the game board to the bottom where the pieces accumulate. The user is given a new piece after the current one reaches the bottom of the available game space. While a piece is falling, the user rotates it in order to fit it in with the accumulated pieces. The object of the puzzle is to fill all spaces along a horizontal line. If that is accomplished, the line is erased, points are earned, and more of the game board is available for play. But if the pieces accumulate and reach the top of the screen, then the game is over. These then are the general, abstract ideas underlying Tetris and cannot be protected by copyright nor can expressive elements that are inseparable from them.36

The court held that the “style, design, shape, and movement of the pieces are expression; they are not part of the ideas, rules, or functions of the game.”37 Thus, using the same seven shapes, the same board dimensions, and the lateral rotating movement of the shapes through the board resulted in a finding of infringement.38

Overall, the results in the video game cases are consistent with the basic proposition that the rules of a game are not copyrightable—notwithstanding that the courts often implement an idea/expression analysis. However, they often conflate a game’s rules with the idea, i.e., an abstraction, of the game—which results in many specific functional features gaining copyright protection when they should not. Again, a functional aspect such as a rule is uncopyrightable regardless of whether it’s an abstract idea or a specific implementation. But this of course begs the question: How do we define rules?

How Do We Define Uncopyrightable Game Rules?

The standard for what constitutes a video game rule should be simple and commonsensical. I here propose the following definition for the rules of a game: the limitations and affordances of the game. This definition is explained by the world-renowned game designer and scholar Jesper Juul:

Rules specify limitations and affordances. They prohibit players from performing actions such as making jewelry out of dice, but they also add meaning to the allowed actions and this affords players meaningful actions that were not otherwise available; rules give games structure. The board game needs rules that let the players move their pieces as well as preventing them from making illegal moves; the video game needs rules that let the characters move as well as rules that prevent the character from reaching the goal immediately.39

Juul’s definition is in accord with other widely accepted definitions of game rules.40

Applying this definition, the line between the rules and the expressive, nonfunctional aspects of a game is clear. Consider the game of chess. The rules of the game are familiar and, even if invented today, uncopyrightable. Yet creators often receive copyright protection for chess sets.41 A nautical chess set and a Michelangelo chess set would have identical rules (i.e., limitations and affordances). The differences lie in the expressive/nonfunctional elements of the games. That is, the king of the nautical chess set might be a ship captain; the king of the Michelangelo chess set might be David. Altering these aspects would not have any impact on the functioning of the game. And all this is true regardless of whether the game is in board or electronic form.42

Take, as another example, a Simpsons-themed chess set. The depiction of Marge, Homer, Bart, and the other Simpsons characters are surely copyrightable. But none of the underlying rules for chess are copyrightable, even if invented today.

Take an even simpler example: Tic-Tac-Toe. The rules of the game are well known:

  1. The playing field is a three-by-three grid.
  2. Two players alternate marking those squares, the first player using a mark belonging to herself and the second player using a different mark belonging to himself.
  3. If one player places three of the same marks in a row, that player wins.
  4. If all squares are filled without a winner, the game is a draw.

Generally, the first player’s mark is an X and the second’s is an O. But the rules would not change if the X was changed to an A, a banana, or a monkey, and if the O was changed to a B, an orange, or a giraffe. The type of mark doesn’t matter to the functioning of the game, provided that the two marks are distinguishable from each other.


When we think of the rules of the game as the limitations and affordances of the game, then some features, which may not be a part of a game’s idea, are nonetheless uncopyrightable. Let’s go back to the Tetris case. There, the court found that the shapes of the pieces (which dictate how and where the shapes fit on the board), the movement of the pieces (which dictates how to place the shapes on the board), and the size of the board (which dictates exactly where to place the shapes on the board) were copyrightable. This is wrong. These features are all limitations and affordances of the game—and they are all uncopyrightable rules. By filtering out only the uncopyrightable idea of the game, some game rules may found to be copyrightable. This is wrong. Games rules have never been copyrightable, and the idea of a game is just one uncopyrightable aspect of a work. This may be somewhat discomfiting, where the game is comprised almost exclusively of rules—such as in Tetris, but that is no excuse to find otherwise. As explained in detail above, the statutory language and legislative history supporting that language both confirm that neither abstractions nor functional features are copyrightable. Focusing on abstractions only is error. Thus and in conclusion, to determine the uncopyrightable aspects of a video game, a court must not only define the uncopyrightable idea of a game, but also its uncopyrightable rules.


1. 17 U.S.C. § 102(b).

2. See H.R. 11947, 88th Cong. (1964); S. 3008, 88th Cong. (1964).

3. Copyright Law Revision: Hearings on S. 597 Before the Subcomm. on Patents, Trademarks, and Copyrights of the S. Comm. on the Judiciary, 90th Cong. 192–99 (1967).

4. S. 543, 91st Cong. (1969).

5. H.R. Rep. No. 94-1476, at 57 (1976), reprinted in 1976 U.S.C.C.A.N. 5659, 5670.

6. U.S. Copyright Office Factsheet FL-108: Copyright Registration of Games (Dec. 2011),

7. 86 F.2d 958, 961 (1st Cir. 1936).

8. 42 F.2d 782, 782 (S.D.N.Y. 1929); see also Landsberg v. Scrabble Crossword Game Players, Inc., 736 F.2d 485, 489 (9th Cir. 1984); Durham Indus., Inc. v. Tomy Corp., 630 F.2d 905 (2d Cir. 1980); Affiliated Hosp. Prods., Inc. v. Merdel Game Mfg. Co., 513 F.2d 1183 (2d Cir. 1975); Morrissey v. Proctor & Gamble Co., 379 F.2d 675 (1st Cir. 1967); Affiliated Enters., Inc. v. Gantz, 86 F.2d 597 (10th Cir. 1936); Hoopla Sports & Entm’t, Inc. v. Nike, Inc., 947 F. Supp. 347 (N.D. Ill. 1996); Chamberlin v. Uris Sales Corp., 56 F. Supp. 987, 988 (S.D.N.Y. 1944), aff’d, 150 F.2d 512 (2d Cir. 1945); Seltzer v. Sunbrock, 22 F. Supp. 621, 630 (S.D. Cal. 1938); Russell v. Ne. Publ’g Co., 7 F. Supp. 571 (D. Mass. 1934).

9. 49 F.3d 807, 810 (1st Cir. 1995).

10. Id. at 815.

11. Id. at 816 (footnote omitted).

12. Id. at 818.

13. Lotus Dev. Corp. v. Borland Int’l, Inc., 516 U.S. 233 (1996).

14. Borland, 49 F.3d at 815.

15. No. 81 C 6099, 1981 WL 1388 (N.D. Ill. Nov. 3, 1981).

16. Id. at *2.

17. 547 F. Supp. 222, 225 (D. Md. 1981). Asteroids is well known, but it’s near impossible to find a version of Meteors. It was never widely distributed despite the court’s finding of no infringement.

18. Id. at 228.

19. Id.

20. Id. at 224–25, 229.

21. 672 F.2d 607 (7th Cir. 1982).

22. Id. at 617.

23. Id.

24. Id. at 617–18 (emphasis added).

25. 862 F.2d 204 (9th Cir. 1988).

26. Id. at 209.

27. Id.

28. 400 F.3d 1007 (7th Cir. 2005).

29. Id. at 1012.

30. Id.

31. Id.

32. Id. at 1014.

33. Id.

34. 863 F. Supp. 2d 394 (D.N.J. 2012).

35. Full disclosure, this briefing was done by me, on behalf of Xio and its game, Mino.

36. Id. at 409.

37. Id. at 411 (emphasis added).

38. Id.

39. Jesper Juul, Half-Real: Video Games between Real Rules and Fictional Worlds 58 (2005).

40. See, e.g., Oxford English Dictionary, Rule (2011) (“a regulation determining the methods or course of a game or the like”); Bruce E. Boyden, Games and Other Uncopyrightable Systems, 18 Geo. Mason L. Rev. 439, 450 (2011) (“[T]he rules of a game are sometimes thought of as instructions for playing the game, but they are not; rules do not tell players precisely what to do. Rather, they place broad constraints on what players can do and conversely define certain actions as valid within the scope of the game.”).

41. See, e.g., U.S. Copyright Registration No. VAu000362713 (Mar. 24, 1997) (“Nautically designed chess set”); U.S. Copyright Registration No. VAu000666397 (Mar. 28, 2005) (“Chess set, sculpture of Michelangelo”).

42. See generally 2 William A. Patry, Patry on Copyright § 4:20 (“Computer programs that permit the play of electronic chess games may be protected, but on a basis no different from any other computer program. The actual chess game pieces are sometimes highly creative works of sculpture and may be protected as such, as may a ‘chess set’ that consists of original chess pieces and original text sold as an ensemble.”).


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