Game companies do this all the time. Namco had a patent on the idea of "a minigame playable during a loading screen". Splatoon on the Wii U had a minigame you could play while waiting, but as it was during the multiplayer matchmaking process, not loading, it avoided the patent.

But there is no IP in the gaming industry more vigorously defended than Tetris. The Tetris Company LLC has:

* trademarks on the name Tetris, the wordmark, and the word "tetrimino" to refer to the pieces, of course

* trade dress rights on otherwise generic elements, such as the shape of the tetromino pieces themselves and the Russian folk song "Korobeiniki", when used in video games

* copyright on the concept of "a video game where tetromino pieces fall and you must arrange them to make lines". You'd think that this element would not be copyrightable, but Atari v. Philips, which concerned Pac-Man and clones thereof, established that a video game is copyrightable as a form of audiovisual performance, not just program code, which means that if a game looks and behaves enough like a copyrighted game such as Tetris ("substantial similarity"), it can be infringing. And it's near-impossible to make a falling-tetromino puzzle game without making it look and behave like Tetris. Henk and Alexey have retained some of the best lawyers American capitalism can buy, and they've successfully litigated copyright actions against cloners of Tetris and have had "Tetris clone" material seized at the border on copyright grounds.