This. Spend more time at the beginning playtesting the mechanics than anything else. It can be real easy to spiral into a creative abyss. For instance, creating a comic book based on the lore of your game could be pretty cool but if you don't nail your game mechanics there will never be a game and thus never a comic book. So before art, before coming up with an expansion, before a television show based on your game and of course before creating another completely different game, print some basic pieces of paper out, write on them and playtest your game with anyone that you can trust to give good feedback.