Hello,

Are there any clear rules regarding the gameplay?

What if one game's gameplay is similar to another game's? Is that illegal?

regards,

lingo1357 said:
Are there any clear rules regarding the gameplay?

I'd say no, but when you get more specific, say down a genre, there can be some generally followed rules you can follow. Like a shrinking circle in battle royals.

lingo1357 said:
What if one game's gameplay is similar to another game's? Is that illegal?

Nope. PUBG, Fortnite and Apex legends are all similar games, but no one got in trouble for taking inpiration/ideas from the others. PUBG did actually try to sue Fortnite for taking their battle royale concept and making another game with it, but has since dropped it.

Hope that helps!

lingo1357 said:
What if one game's gameplay is similar to another game's? Is that illegal?

Usually no, but there are always details. Anything which is unique and distinctive can be covered by many different IP laws. Generally gameplay as an abstract philosophy can't be protected, but any unique, distinctive elements in a game may be covered by laws around trade dress, visual and audio elements covered by copyright, and so on.

As a general rule, don't take anything that is distinctive to a single game. If something is used by a wide genre of games feel free to take the broad theme but not the specific, distinctive elements. There are also factors around the cost and recovery around lawsuits. Different companies use different math around what they are willing to send C&D letters about, what they are willing to sue over, and how far they're willing to take it.

There is no bright line. The concept of a platform game is wide open. A platformer that feels exactly like Super Mario Brothers but uses different themed characters will likely raise alarms but probably not hit a lawsuit. Give the players red and green outfits and stomping on turtles and you're quite likely (but still not guaranteed) to get letters from Nintendo. The closer you approach their property the higher the risk of lawsuit and the worse your risks of losing. Some companies are far more protective than others. Different products are more heavily protected than others.

This is a creative industry. In general try not to clone other products, and instead follow your own original ideas. If you're concerned about getting too close you should talk with a lawyer familiar with the industry in your part of the world. If you can't afford to talk to a lawyer, you definitely cannot afford a lawsuit so stay away from other products.

Rule of thumb: just “ideas” can not be patented. In a general case, it's hard to definitively derive what is copied, from which source, and to which extent. In the game dev, this is true as well. Specific (and very blatant) case: there is a game “Words" on Facebook, which is a carbon copy of the Scrabble board game. If they got away with it, you can as well. Moreover, big companies usually do not hunt us, small fries; and smaller companies have better things to do. So, you should not worry.

One interesting bit. There was news that LOTR game developers patented their “nemesis” mechanic. If you read into it, you realize that did not technically patent a mechanic/idea, they patented the implementation of a mechanic, which is a very narrow definition. AFAIK these types of IP cover situations like stolen source code and one-to-one copies, but any deviation in the mechanic internals would produce a different implementation, which is not covered. “Why would they do it then?”, you may ask. Because they love “patent bullying”, I guess. Lawyers are extremely expensive, and participation in litigation will tank the finances of both parties in case of a legal battle over IP. Warner Bros has a lot of cash; more than their potential opponent, so it will survive while the opponent won't. This patent is needed just as a potential motive to start the legal process, contents do not matter much. Again - you should not worry.

Back on track. Do not use recognizable names. images, logos, etc.; they are protected. If you would like to pay homage via a clever reference - well, ask yourself: does the inclusion of this piece of intellectual property can theoretically make its owner lose money? Do you piggyback on its success to get something you would not get otherwise? If you answered “yes” to any of these questions, you should not do it.