It's extremely difficult, but there are enough to show that it can be done. Most people just don't want to. The secret seems to be infinite playtesting of infinite variations.
Factorio and Minecraft each took over a decade, and scrapped and redesigned core game mechanics many times. Half-Life 2 had a completely different storyline one year before release, and Ocarina of Time had a completely different environment. The Witness spent years testing puzzles and layouts in a blocky programmer world before finalizing it and making it beautiful. Baba Is You obviously also spent ages testing and trying a zillion combinations of puzzle elements. And those are just the ones at the top of my head.
You don't need as much to make a slop shooter that's moderately fun and relies on graphics and action gameplay. However, that market is saturated precisely because it is easier.
Factorio and Minecraft each took over a decade, and scrapped and redesigned core game mechanics many times. Half-Life 2 had a completely different storyline one year before release, and Ocarina of Time had a completely different environment. The Witness spent years testing puzzles and layouts in a blocky programmer world before finalizing it and making it beautiful. Baba Is You obviously also spent ages testing and trying a zillion combinations of puzzle elements. And those are just the ones at the top of my head.
You don't need as much to make a slop shooter that's moderately fun and relies on graphics and action gameplay. However, that market is saturated precisely because it is easier.