• The game display
  Here we're referring to the window, terminal, console, or other display the game must control.

• Screens or locations
  Here we're referring to both the different control screens a user might see (game setup screens, option screens, etc) and all the different game locations (rooms, maps, etc) the storyline might take the player to.

  In general, our key focus for these will involve establishing their dimensions, the background, and any captions.

• Objects
  Objects include nearly all the characters and physical items (weapons, vehicles, etc) the player might interact with, plus all the interface/control objects (buttons, sliders, etc) the player interacts with.

  Objects will have a variety of properties, including their current location, direction and speed of movement, physical traits, abilities, behaviours, responses to events, etc.

  Objects may also have a current visual representation on screen, which we'll refer to as a sprite.

• Events
  Events include all the things that happen during the game, causing changes in the status or behaviour of objects.

  There are a tremendous number of different event types in most games:

  • I/O events (such as the player pushing a button)
  • interaction between objects
    - a character picking up an item,
    - a character getting hit by an item,
    - a character encountering another character,
  • timed events,
  • to movement events (e.g. an object moving outside the room),
  • creation/destruction events (when an item is first created or destroyed).

  Each event will have a handler - a routine or technique that is applied to determine game behaviour when the event takes place.

First, we'll look at some basic handling of each of these with a scripting language (Python, using the PyGame extension).