Gameplay Programming – They came from Space

They came from Space

Design synopsis: 


The game subject of this report was inspired by the arcade game “Space Invaders” developed by Taito in 1978. The original game itself was inspired and influenced by Atari’s Breakout, another staple of arcade machines. “Invaders! Probably from space!” is a re-interpretation of the classic, the game title is an homage to the episode “Anthology of Interest II: Raiders of the Lost Arcade” from the cartoon “Futurama”, in the episode aliens attack the earth and they do it just like if they were in “Space Invaders”.   

“Shoot’em Up” games are still popular these days. They were ancestors of modern first-person shooters, without “Space Invaders”, Doom and Halo wouldn’t exist. 


Some considerations and issues I faced: 

  • Fidelity: The concept of the game is basic on the surface, so the first objective was to make a contemporary replica of the arcade game. Specially commanding the alien ships separately and making only those in the front shoot. 
  • Adaptable: making the game adaptable and scalable to fit different screens ratio. 
  • Innovate: after recreating the “classic”, the next hurdle was to add something meaningful, but not game breaking. A screen wrap and power up systems were implemented, two easy to code and impactful systems.  

Installation instructions 

  • PC build: unzip the files in an empty folder, double click on the .exe file. Click “Play! “on the window. Move with “WASD” keys or arrow keys. Shoot with a left-button click on a mouse or space key.  
  • Android build: tap on the .apk, install.  Swipe to move, tap to shoot.

Instructions for playing 

  • Movement: The player uses “A” and “D” or the equivalent arrow keys, swipe your fingertip left or right on mobile. 
  • Shooting: press “Space”, click the left button on the mouse or touch the screen on mobile. 

Workshop references 

The Game Manager, the array and the tile creating workshops were those that impacted development the most. 

  • The game manager: being able to have one game manager, a singleton, helped keeping track of all the variables, prefabs and UI. 
  • Arrays: to create a grid, formation, for the aliens and to command them together. 
  • Tile creating: keeps track of the alien ships and shooting and drops. 

 All the above made the programming and the scripts more sophisticated and flexible for future uses.  

Implementation outline 

Implementation plan: 

  • Replicate alien behaviour from original  
  • Replicate ship behaviour  
  • Add new game systems 
  • Add start, end screen and in-game menu 
  • Test 

Some script were inspired by workshops: 

  • Tileobj: this script sets the single alien ships and stores all the information needed to track them. It was modified to meet the needs of this specific game and to be more flexible for future use.  
  • CameraSetup: the script was modified to only include what’s relevant to the game and to make it more flexible.  
  • Alien_base: based on the script “DisplayArray”, used as “overlord” , to track and control all of the alien ships at once. 

Asset plan 

Only free assets where used and they found trough a simple search on the Internet.  

  • Space Shooter Template FREE 
  • Standard Assets  
  • Simple UI 
  • Sprites 
  • Icon 

Scene Hierarchy 


  • Alien_Spawn: prefab for the single alien ship 
  • AlienDisplay: container for all the aliens 
  • Backgrounds: background prefab that handles the movements of the background 
  • Ball_02: alien bullet 
  • Bullet:player bullet 
  • Drop: power up 
  • Main Camera: main camera 
  • Ship@2x: PC 

Gameplay screenshots 

Figure 1 Gameplay video