For example, just because the game is a platform game doesn't mean that the character has to go around hopping on enemies heads collecting power-ups. Developers should constantly re-think how things are done. They shouldn't put combos in a fighting game or floating platforms because another game does. It is better to visualize the flow of the game first, then come up with the more complex game elements. If you create the story first, then the gameplay is bound to the story, and that cuts of the on the fly creativeness that makes a superior game.
Characters are another part of games.
Gamers could talk about the importance of characters until they are blue in the face and still not stress the importance to the proper level. Now that you get the importance of having a solid character, lets see what is involved in making a superior one. They are personality, appearance, and uniqueness. For the most part, video game characters are pretty shallow. That's ok though.