As noted by the U.S. District Court in the Southern District of Texas in 2014, "The parties agree that Bang! and LOTK have nearly identical rules for playing the game." What differs is that BANG! is set in the U.S. wild west of the 1800s and features characters and artwork typical for that locale, while LOTK has artwork and characters based on the historical novel Romance of the Three Kingdoms, which dates to the 14th century. The court denied Davinci's request for preliminary injunction, which would have prevented ZiKo Games from further distribution of Legends of the Three Kingdoms, but it allowed DaVinci to pursue its claim that ZiKo and Yoka "improperly copied protected features" of BANG!
In late April 2016, the court ruled against DaVinci, noting in its summary that "Bang!'s characters, roles, and interactions are not substantially similar to those in LOTK. The aspects of the roles, characters, and interactions that are similar are not expressive, and aspects that are expressive are not substantially similar. ZiKo and Yoka are entitled to summary judgment of noninfringement."
The ruling makes for fascinating reading, and you can download a PDF of the ruling here. Some excerpts:
This general rule is consistent with the decision in Baker v. Selden, 101 U.S. 99 (1879), in which the Supreme Court ruled that a particular bookkeeping system was not copyrightable. The language and illustrations that the plaintiff had used to explain his system were copyrightable, but they did not protect the system itself from use by other parties. The Copyright Office has applied the rule that copyright does not protect a system's operation method to games. The December 2011 fact sheet for Copyright Registration of Games states:
Even if the Bang! characters' abilities were not stock, they are still not expressive because they are essentially rules of game play. The character of Rose Doolan, for example, has the ability to strike opponents from a longer distance than other characters. (Docket Entry No. 61, Ex. 6 at 110:6-10). This ability is no more expressive than the ability of a rook in a chess game to take an opposing piece from all the way across the board, as opposed to a pawn that may attack only from the next square. The rook's ability affects other characters or roles in the game because the attack range increases the queen's and king's exposure. But this special ability is neither literary nor artistic. It is an aspect of game play, a subset of the rules that make up the game system.
It's not 2001 anymore, and we now have thousands of people who play Munchkin and have never seen games such as D&D, much less explored the history of those games. We occasionally get social media comments, emails, and even physical letters taking us to task for belittling transgender players. Some of them are heartbreaking.
Speaking on behalf of the entire Munchkin team, it is not and never has been our intent to poke fun at the struggles faced by people who don't match society's gender norms. It has always been our view that the penalty for changing gender in Munchkin derived from its involuntary nature, not the gender change itself, and we have encouraged people to remove the penalty — or the entire effect — if their group found it problematic.