Why are so many games today so repetitive? The enemies monotonous, the puzzles identical, the quests copy and pasted, why are games so boring? If you look at classic games you will find many different enemies in different environments but a lot of games today, even AAA titles fall short on variety, and as such a very common qualm with games today is that they are repetitive. For a game to be fun it can't be repetitive, it has to have variety.
A games structural design can be summed up in three parts: enemy/puzzle design, environment/geography and difficulty curve. The game may have more defined features like combat mechanics, aesthetic, etc. but strip a game down and that is what you end up with. If those three points are put together right, your game is built on a much stronger foundation. But today very little emphasis is put on these and often repetitive, boring games result.