If you find that doing without all of the foregoing makes it impossible to build your game, you are not creative enough to call yourself a game designer. One of the games that made it to the finals of the first Independent Games Festival was about birds called blue-footed boobies, so forget you ever heard of George Lucas and J.R.R. Tolkien and get to work. If a game requires any introductory or transitional material, it must be provided by scrolling text. The secret desire of game designers to be film directors is deleterious to their games and to the industry generally. This desire must be stamped out.
Violence is strictly limited to the disappearance or immobilization of destroyed units.
Units which are damaged or destroyed shall be so indicated by symbolic, not representational, means. There shall be no blood, explosions, or injury or death animations. Explosions and death animations are, in fact, very short non-interactive movies. There may be victory and defeat, and my side and their side, but there may not be Good and Evil. Good versus Evil is the most hackneyed, overused excuse imaginable for having two sides in a fight.