Chris Johnson - Game Designer

Project Slingshot – Physics Puzzle


Project Slingshot

A physics-based puzzle game with a unique take on space sci-fi

Developed By: Chris Johnson

Engine/Framework: Unity 4

Platform: PC

Type: 2.5D Single-player Puzzle

Demo Build Available Here (V. 0.2.3)

Please note, this is an unfinished, in-development demonstrative version of the game, showcasing two early levels of the game. This version includes placeholder assets that will not appear in the final game. I have released this version to show the basic design and aesthetic concept for this game.

Narrative Overview

Project Slingshot places the player in the role of a new employee of the Interplanetary Postal Service (IPS), a government-run organization that delivers parcels and supplies to colonies and settlements on different planets across the galaxy. Due to budget cuts, the IPS has opted to send parcels across the vast stretches of space by loading them into a giant cannon and quite literally shooting them at their intended recipients. This is where the player comes in, because it takes careful strategy and aiming of the cannon to ensure that parcels will reach their target.


 Logo for the Interplanetary Postal Service (IPS)

System/Mechanic Design

Project Slingshot – Visual Design Document

In Project Slingshot, players are given a top-down view of outer space, which can be panned and zoomed much like any RTS game. For practical purposes, this view of space is not to scale. It’s scale has been adjusted so that the player and the player’s target can appear on screen at the same time.

The game space (the portion of the screen showing a star field, that is not occupied by an HUD elements) is occupied by the player’s own space station, the player’s target(s), and any number of environmental obstacles that stand in the player’s way. The player’s space station is the closest representation of the player character in the game, and it features a cannon turret which always rotates to face the mouse, and which fires parcels when the player presses the fire button. The targets are not explicitly labelled as such, but they are referenced in the mission briefing, and always have a similar visual appearance in every level. The obstacles may vary greatly in appearance, ranging from asteroids, planets, or space ships. This adds visually appealing variation that differentiates levels from one another, and creates a more believable game scenario.

The parcels, when fired, travel through space in an almost deterministic manner. A parcel fired in the same direction through the same environment will always follow the same path. But this path is determined by the complex influences of gravity on the parcel as it travels. Thus, players are often unable to accurately predict the path of parcels initially, but with each shot they fire, the paths that parcels take become more clear, allowing players to make each successive shot more accurate as they gain a better understanding of the forces of gravity at play within the level.

In this system, the challenge is a question of “can the player learn the path that the fired parcels will take, and use that knowledge to hit their target?” But to create additional challenge, limits on the number of parcels available. Now the challenge becomes a question of “can the player learn the path that the fired parcels will take, and can they do it before they run out of parcels to experiment with?” This added restriction of parcels serves to mitigate (but not eliminate) a known design flaw, which is that, through brute-force experimentation and a long enough amount of time spent, players are bound to find the correct firing solution and hit their target, even if they did not find that solution through intelligent experimentation and observation.


From left to right: player space station,  asteroid obstacles, target

UI Design

The in-game UI for Project Slingshot was designed to be familiar to players of other games, and also to provide vital information to the player while not cluttering their viewport. In the lower-left corner of the screen, a panel displays the number of Parcels and AGEs that have been used, the number that are available in this level, and, indirectly, the number that the player has left to use.


The  resources panel shows information that is essential to gameplay

Other UI panels function differently, such as the mission objectives panel in the top-right corner and the audio message panel in the bottom-center. These panels contain information that is not always vital at any given point during gameplay, and as such, they disappear from view when the the information they display is not relevant, so as not to block the player’s view of the world space.

objectivespanel_upThe objectives panel is seen as a thumbnail at the corner of the screen.


On mouse-over, the objectives panel expands, showing a list of options. When the

mouse moves away, the panel collapses again into a thumbnail.

Game Design Portfolio of Chris Johnson