Wednesday, November 26, 2008

Moving Around in 2 and 3 Dimensions

Here are some differences between ground-level 3D and top-down 2D environments, and their implications for ease of navigation:
  1. The way the shapes of objects change as the player moves around the game environment. In 2D environments, rigid objects retain their projected shape as they change position and orientation due to player motion, while in 3D environments their apparent shape can change significantly.
  2. The way the angles between objects change as the player orbits around a particular point or travels along a path1, as measured from the camera's perspective. In 3D environments the apparent angles between objects are significantly affected as the player moves around, but remain fixed in 2D views.
For these reasons, a 2D view is generally more stable than a 3D view, as it doesn't change quite as radically as the 3D view when the player moves around the game world. Furthermore, since the view in top-down 2D games doesn't usually rotate as it does in 3D, a typical 2D view is remarkably stable compared to a 3D perspective. A stable view provides a more recognizable context than a more dynamic view, which makes it easier to tell where you are and which way to go.

1. If the player is moving along a straight line, angles between objects will change only if parallax is present.

Wednesday, November 19, 2008

[Offtopic] Software Activation and IP Ownership

Softimage XSI has recently been acquired by Autodesk, the company that owns competing packages 3ds Max and Maya. Users who've purchased XSI through its former owner will now have to deal with Autodesk for any licensing and support issues.

Since XSI requires the software to be activated online before it can be used, existing users will be at Autodesk's mercy when reinstalling XSI onto their computers following catastrophic data loss or when transferring their license onto a new computer. These users, who purchased XSI with Softimage's particular activation policies in mind, will now be subject to Autodesk's activation policies and may even be required -- if Autodesk should so desire -- to agree to Autodesk's more restrictive licensing terms before Autodesk will agree to activate any copies of XSI purchased before the change of ownership.

Perhaps things will turn out okay for current XSI users, but there's no guarantee that will be the case. Whenever you use software that requires activation, you remain at the mercy of the software's copyright holder, which may change without warning and without any remedy to you, the user.

Thursday, May 15, 2008

Failure by Random Numbers

Failure by random numbers can occur whenever the random processes that determine failure aren't significantly influenced by the player's choices, giving players little or no meaningful control over the outcome of their actions. For the most part, games should be designed such that players may improve their chances of success according to the choices they make in the game, giving them meaningful control over their future.

Friday, January 18, 2008

Cause and Effect

Principle: Avoid responding to the player's actions with behavior that is contrary to reasonable player expectations, as it breaks the implied "contract" between the player and the game designer.

Players cannot form a useful mental model of the game world when things happen unexpectedly or without an apparent cause. Players should be able to understand the laws at work in your game's environment, and to make appropriate deductions based on their understanding of those laws.

If unexpected or incongruent behavior is desired, players should ultimately be able, by virtue of the game's design, to reconcile such behavior with their operative mental model of the game world -- which by its nature is allowed to change as the game progresses.

Thursday, January 10, 2008

Meaningful Mistakes

Principle: Sometimes a player's mistakes aren't really mistakes. If a player has no good reason to believe a particular action might lead to failure, then failure should not be blamed on the player.

Failure by surprise occurs when the player's actions do not appear as if they should lead to failure, because the relationship between action and outcome is either obscure or counterintuitive, or because the element that makes a particular action lead to failure is presented too late for the player to react to it. King's Quest and Dragon's Lair are known for this kind of failure mechanism, where the wrong move can easily result in unexpected death or failure1.

A game should generally provide enough clues for players to anticipate danger, and should otherwise give players a fair chance to react to any surprises.


1. See
Ways to Die/Lose in King's Quest and Let's Fail Dragon's Lair v2.0 (not safe for work).

Monday, January 07, 2008

Walkthrough? I Don't Need No Steenking Walkthrough!

Principle: If a game requires a strategy guide or walkthrough to complete, it's broken. If the game may be completed without one but nevertheless provokes a not insignificant number of players to consult one, it's just as broken as before.

Rationale: Completing a game should require no external clues. A player's failure to figure out a particular puzzle without outside help is actually the designer's failure to provide sufficient clues within the game. The game world is missing essential information; the game is broken.

Exceptions: If a game mechanic explicitly involves the application of external information, this principle does not apply.