Overt use of information in most games consists of a simple distinction between public and private; the fog of war, the cards in an opponents hand, the items in the Clue envelope. In some games it’s as subtle and pervasive as not knowing what the outcome of a die result will be or the intents of another player. In other games, the mental organization of the information is of particular importance. The pervasive HUD in games is an outgrowth of this need to manage information, stressing or removing ambiguities, in order to provide a specific gameplay experience.
Cards games are noteworthy in that they defer to players who understand the relative chances of different hands. Adding a clear and highly designed expression of the chances inherit in a player’s hand and the potential results of different discarding choices would transform it into a new, and likely less compelling game. While reading this information from the cards is ‘part’ of the game, reading the specific information contained on each those card is not. Obscuring the number and suit of a card, potentially confusing the player or forcing them to spend more mental energy deciphering them, would be detrimental to the game. The clear and unambiguous presentation of this information is necessary for the intended play of these games.
All games contain information, and the play of the game is based in part on what information has game meaning and in what way. HUDs in computer games help keep non-gameplay related ambiguities minimal, allowing the player to focus on a particular set of information and thus engage in a particular form of gameplay. It can be easy to say simply that the removal of the HUD (in games like Killzone 2 or King Kong) increases immersion. After all, we don’t need a HUD for a film, right? The information aspect of games though makes the random user guided access of information, typified by the HUD, important. I believe that evaluating the effects of a change in HUD on the qualities of the game experience is not possible without evaluating the specifics of the game being played.
These specifics are often additionally influenced by the people playing the game. While the defined rules of an FPS may stay consistent between two groups of players, the gameplay between each group may be noticeably different. To a group of novices the game is about properly aiming the gun at an opponent, to a group of experts this ‘game’ may have been mastered or ‘solved’, and is limited and boring. As such their game focuses on co-operating to control tactically valuable parts of the battlefield. The first type of play may require the player to possess an enemy tracking system less it be too difficult, whereas in the second example players may eschew such a HUD element (turning it off) in order to focus on gameplay built around situational awareness. An example of this is the distinction between normal and hardcore modes in Call of Duty 4: Modern Warfare. In the hardcore modes, health is reduced and the radar is removed. A player who doesn’t understand the map or how to play defensively will find the mode particularly difficult or frustrating, while an expert will find managing the new ambiguity particularly engaging.
In comparing games to movies in the discussion of HUDs it should be noted that information in film can be presented as needed, when needed. Games also present situationally important information (in the form of feedback) but are typically not sophisticated enough make sweeping assumptions about what the player needs to know when. In these cases having information constantly accessible is safer for game play than having it obscured when needed. Furthermore, the relative meaning and import of various, and very specific, changes in the game state are beyond the sophistication of most games. A game may be able to hi-light a killing blow, but managing the emphasis on the subtle moves that led up to it is a far more difficult feat, one best left to the player. So long as they have the information to understood the sequence in the first place.