There are developers and publishers finding huge success with brand-new ideas, but the majority of profitable games take proven ideas and add a bit of spin to them to find an audience.
There's nothing wrong with copying the work of other games, or other genres, the important thing is to know why you're copying, and do something interesting with your own product.
"Look at the game you are thinking of copying, the one that got all those YouTube views, and look at why it worked, the decisions and choices, the objectives," Volume and Thomas Was Alone developer Mike Bithell wrote in a recent blog post. "How the surface of the game achieved the outcome, and then come up with something different that may duplicate some of that success."
He describes a meeting where his then boss asked how to make a Minecraft game, and instead Bithell sat down and made a list of what Minecraft did well. He was focused on why it was a success, instead of simply looking to rip off the topical aspects of the game or its specific design.
"So don’t make a horror FPS. Make a different game that facilitates YouTube personalities looking foolish, doing dramatic reactions," he continued. "Don’t make a roguelike, work out a way to make a game that can provide an interesting base of single player content for 100 videos. Don’t make a sim game where you clumsily interact with the world, work out a way to allow players to tell jokes through interaction."
Stealing is okay, but do it with purpose
People copy design ideas all the time, and it's rarely controversial. The trick is to copy other games in a controlled way; you have to understand why you're being informed by another game, and then find a way to do what that game does well in a way that also expresses what you'd like to do with your title. It's not about cloning games, it's about learning how to take what you want and tweak it enough that it no longer feels like a past game.
This is a process that Blizzard has used to great success, and they're not shy about sharing it.
"Let's take a game that we all love playing, do what we want to do to make it ours, just like we've done with every single game from the past. Vikings was Lemmings. Rock and Roll Racing, name any of those car games out there. Warcraft came from Dune, so it's the same thing with Heroes of the Storm," Sam Didier, a senior art director at Blizzard, told Polygon in an interview about Heroes of the Storm. "It's like, we take a game that we like and then we make our version of it. If we like it, it turns out that people like it as well."
Blizzard also have the strength of vision needed to throw out genre staples such as the item shop and the sort of single-map play that defines the most popular MOBA releases. Blizzard may start with inspiration from other games, but they know that the ideas and inspiration they take is only the beginning. Hearthstone is just another card game on paper, it's the detail and art put into its design and execution that make it a Blizzard game. But no one is going to argue the idea of is novel in any way.
That freedom to begin with a game they love, and then experiment with what it does well is a large factor of Blizzard's success.
"We usually just make the games where we're having fun making them, and that's really the main thing. We're not necessarily thinking too much about how are we gonna go in and conquer this sort of thing or how are we gonna crush this sort of thing," Didier said. "We go, 'Hey, this would be fun.' We've made that with pretty much every game we've ever made. 'Oh hey guys, man, we love Everquest, we should do something. That was World of Warcraft, and that was the whole thing."
Give yourself the freedom to steal
There's nothing wrong from lifting mechanics or ideas from others games as long as you know why you're doing so, and know what to do with those ideas once you have them. Many developers and critics dismiss even incredibly popular games like the recent mobile Kim Kardashian title instead of trying to understand why it appeals to people.
The setting is far from the usual dystopian future or space battles of "hardcore" video games, and it pulls in a diverse audience. It also features progressive design when it comes to relationships, furthering its appeal among many demographics that aren't usually served so gracefully by video games.
Rock music that was only influenced by rock music is Nickelback
You can't argue with the game's success, and attributing that success solely to Kardashian's appeal or the vapidity of a mainstream audience is short sighted. The game does things well, and once you stop dismissing things you don't like and instead try to learn from them you'll find even more things to copy in your games.
Remember that the best rock music was influenced by everything from country to spirituals and rhythm and blues. That's how we got Elvis and Johnny Cash; they stole from interesting sources and mashed them up to create something new, filled with spirit (and a splash of cultural appropriation.) Rock music that was only influenced by rock music is Nickelback.
So steal, copy, and rip off ideas from other games. Just understand why you're doing it, and then put your own spin on it. Uncharted may have ripped off the feeling and tone from Indiana Jones, but it's your job to figure out how to go deeper, to the writing and level design, to figure out what you can take for your own game if you're after that sort of feel. Don't steal Nathan Drake, steal the reasons people love Nathan Drake.
"Go one level down on any design," Bithell wrote. "Work out how something ticks, and you may find yourself producing something special."