Game Engine Foundations

COS 170 - Introduction to Game Engine Design

Game Engine

The term "game engine" arose in the mid-1990s in reference to first-person shooter (FPS) games like Doom by id Software.

Prior to this, the software running the game was the game.

Following, a separation grew between the engine and the game.

The architecture of the software differentiates game engines from game software.

Game Engine

Game engines:

• render a scene
• detect collisions
• simulate physics
• manage audio
• handle user input
• handle network communication
• load/save data to/from media
• animate skeleton systems
• animate particle systems
• interface with AI systems
• optimize the scene
• manage memory and resource usage
• manage state of game

Runtime Engine Architecture

Game Engine

For this course, we will focus less on separating the game from the engine and more on what are the key components that make up a digital game and game engine.

We will use variables and different resources (graphics, audio, etc.) to "tune" each game to be different, but the engine and game will be tightly coupled.

Types

• First Person Shooter (FPS)
• Platformers
• Fighting
• Racing
• Real-time Strategy
• Massively Multiplayer Online Game (MMOG)
• Role-playing Game (RPG)
• Sports
• Puzzles
• Simulation
• Digital conversion of games

study: FPS games

• Wolfenstein 3D
• Doom
• Quake
• Unreal

study: FPS games

Wolfenstein 3D (1992)

• "grandfather of 3D shooters"
• Engine was licencsed or heavily derived: Blake Stone, Corridor 7, Operation Body Count, Super 3D Noah's Ark, Rise of the Triad, Ken's Labyrinth

study: FPS games

Doom (1993)

• id Tech 1
• Powered Doom and Doom 2: Hell on Earth, Heretic, Hexen: Beyond Heretic, Strife: Quest for the Sigil, Hacx: Twitch 'n Kill, Freedom
• Inspired Build Engine (Ken Silverman), which powered Duke Nukem 3D, Shadow Warrior, Blood, Redneck Rampage, Witchaven, William Shatner's TekWar, PowerSlave, Extreme Paintbrawl

study: FPS games

Quake (1996)

• id Tech 2
• Powered Quake 2, Quake 3 Arena, Heretic 2, SiN, Kingpin: Life of Crime, Daikatana, Blade, Warsow, UFO: Alien Invasion, X-Men: The Ravages of Apocalypse, Half-Life
• True 3D rendering
• Engine reduces 3D complexity to increase speed, precalculates lighting and shadows, sectioned the map to increase speed, sped up rendering and rendering order, used 3D hardware acceleration, provided network play.
• Inspired the Unreal Engine

study: FPS games

Unreal (1998)

• Unreal Engine 1
• Integrated rendering, collision detection, AI, visibility, networking, scripting, file system management
• Advanced software rasterizer and hardware-accelerated rendering
• Designed to be extensible and improved over multiple generations of games
• Powered: Adventure Pinball: Forgotten Island, Disney's Brother Bear, Deus Ex, Duke Nukem Forever, Harry Potter and the Chamber of Secrets, Nerf Arena Blast, Rune, TNN Outdoors Pro Hunter, X-COM: Enforcer

basic game

Basic game elements

1. Main Menu
2. Game Loop (may be recursive)
   1. Start
   2. Middle
   3. End

basic game: main menu

The main menu is the landing page or "cover" for the game. The tone of the game is presented here. Players should be able to get help if they need it.

• game title
• set up and start game
• credits
• help
• high score
• options and configurations
• quit

basic game: game loop

After the game and level are started, the game engine goes into a not-quite-infinite loop: the game engine stays in the game loop until the player is dead, the player has won, or the player has quit.

Typical actions done by engine in game loop:

• render graphical and aural assets
• handle user interaction and network communication
• enforce constraints and rules of game
  • simulate physics
  • detect collisions
• update game state: health, score, coins, lives
• load/unload resources: level, models, textures, sounds, music
• handle AI interaction

breakdown: tic-tac-toe

What are the key elements of the game Tic-Tac-Toe? (game)

If we were to make a clone, what code will we need to write and data to store

breakdown: pong

What are the key elements of the game Pong? (game, blog, source)

If we were to make a clone, what code will we need to write and data to store

game states

game states