We want to create a new game, often times because we played one. So that we got inspired and somehow we want to make our own version of it. Maybe we are working for a company which spotted a market opportunity. So that we start studying the games belonging to that market, try to reproduce the best things.
Games industry is very endogamic. We tend too much to take inspiration from the inside of it. But if we see the best products out there, they take a lot from the outside and bring it to the inside.
Days ago I was talking about the TikTok of puzzle games. That is a way of looking outside. You just study the apps market and think in a better UX for some classic game. It often works like that. If you look at games like Royal Match, they took well known mechanics and the real twist is completely on the UX side.
Another great reference is nature. From nature many game designers created memorable gameplay experiences. Think in Japanese legend Shigeru Myiamoto and the story of how The Legend of Zelda was conceived. If you like to walk and you really start observing you notice that nothing in nature is wrong. Recent game The Ants: Underground Kingdom is another evidence of the power of nature. Especially if you want to get better ideas on gameplay and lore, nature is the way.
Art, toys and objects without purpose are also a great way of getting inspired. The history of videogames is full of examples like that. Think in the indie success GRIS or the mobile game Monument Valley. There is not a superhigh challenge, nor a specific deepness in their economies. The Players can just enjoy the overall game feel.