What is the difference between a game, a demo, and an engine?

A Game is playable.

A demo is not.

An Engine is part of either a Demo or a Game. For instance, the Grahics Engine, the Sound Engine, the Network Engine, etc.

Engine
Typically people are talking about the 3D engine. The pieces of code that draw and update the visuals you are seeing. You also hear about the game engine alot which would be the code that processes the game rules. People are starting to refer to the AI as an engine, too. I guess the common thread here is that an engine takes fuel (data) and gives output (graphics, sound, object control).

Game
There is a very formal, mathematical definition of a game, but I doubt you care. Come on! You know what a game is.

Demo
There are several types of demos. There are game demos that give you a sample (a few levels usually) of the game. There are ''demos'' which are cool to look and listen to programs written to impress other geeks. There is apparently a big scene of this in Europe. Go figure. Software demos let you try out software. Usually these do not let you save your work or have missing features. Then there are demonstration programs (for all types of things) that give you a program and source code to learn from. Of the graphic varieties of these, OpenGL demos are clearly the superior to the Direct3D demos. Muhahaha!

Mike Roberts
aka milo
mlbobs@telocity.com

Some clarification:
There are three type of demos

1. A demonstration product. This shows you what the actual program that they want you to buy can do.


2. A game trial. The game is given to you, but only with a limited amount of gameplay. Usually this means a few levels, but could also mean missing areas, lack of certain weapons, etc.


3. A "demo." This is a program that''s sole purpose is to entertain your senses. Typically visual, quite often with a music score, and always, ALWAYS optimized for speed and file size {and sometimes processors.} These are produced by people in the "demoscene" or "demo-scene." Those that created the earlier demos could easily have taught Carmac a few things about 3-D in realtime. If they actually did, I don''t have any evidence.

Hope that helps

---Sonic Silicon---