One element of some games that sometimes seems to be an afterthought, is the idea of visibility for the player. Primarily I'm talking about the visibility of the User Interface (UI) elements. Part of the reason for this perhaps, is that if the UI in a game is good enough you really don't have to think about it. The reason you don't have to think about the UI? Because it's easy to read, understand, and just continue playing the game. Deciphering what the UI is telling you should not be a chore. The difficulty of your game should never be artificially inflated because it's impossible to read information that you absolutely need to play the game.