Propulsion: Gameplay Overview

This game uses the theory of general relativity, that being how time flows slower for those in a gravitational field, to provide the player with an arcade-style game. In play, the player controls a spaceship that goes into space, after taking off from Earth. As the player escapes the gravitational field, by getting further away, time passes faster on the surface of Earth. The current year on Earth is always displayed at the top of the screen; this is also the player’s score value for their current run. The player can land on the surface, hundreds of years later, and encounter different civilisations throughout history. Each civilisation will be on the planet surface for a certain timeframe, for example, with the Roman Empire this would be between 600 BCE and 300 CE. The cycle of taking off and landing at different civilisations in time continues until the player inevitably dies.

The game is designed for mobile and can be played by holding down the screen to propel a spaceship into space, and letting go to make the rocket go back down. At its core, this is an endless runner that asks the player to continue playing and reach insanely high scores, or die trying. Death comes very quickly and players are prompted to retry, to see if they can beat their previous attempt. Because of this, the core minute-to-minute gameplay loop needs to be very engaging and ensure that the player wants to come back for more.

The core gameplay is about avoiding asteroids and collecting fuel pickups to keep using the spaceship’s thrusters; both of these fly in from the sides, as the player can only move up or down. Signals at the sides of the screen will indicate when one of these is coming, and where it is coming from, so the player can move accordingly. These items will come in waves, for example three asteroids across from the top right and two from the bottom left, that will be predetermined to create fun patterns for the player’s to predict and avoid. Players will eventually learn these patterns, become more skilled at the game and achieve higher scores.

To counteract the fatigue of constantly losing, there is an upgrade system that allows the player, whenever they land on the surface of the planet and encounter a new civilisation, to select a new module to add to their spaceship. This new module will drastically change the game, such as by making the spaceship’s thrusters fire in bursts or adding a rechargeable shield that protects against asteroids, and the player is encouraged to mix and match upgrades in each attempt.

The spaceship will grow in size as more modules are added; however this makes the player an easier target for the asteroids. Players do not need to land on the surface and select a new module to add and, instead, may choose to stay in space to stay smaller. In this way, the game rewards different playstyles.

How the game will look is discussed more in the visual style, however, the below sketches give an idea. You can see that the rocket is in the foreground with the civilisation's capital city in the background. I have also sketched ideas for simple people, which will be at the bottom, in the foreground.