Balloonium

Balloonium is a 2d physics based game where you play as a balloon trying to escape a procedurally generated cave system. It got its start as a team project for UBC's CPSC 427 video game programming course. My team and I have since decided to continue working on it and are aiming for a release some time in early 2025. Below are details on our game's level generation pipeline and audio system.

Procedural level generation and asset placement

Level generation begins by running wave function collapse to generate our raw level gridmap data. The input image uses the green colour channel to represent walls, red to represent wall hazards (like stalactites, mud bubbles and spiders) and black for empty space. Using WFC allows us to loosely specify the style and shape of levels we want. The input images are created using MSPaint.

We use flood fill to find all the rooms in the grid, then proceed to fill all the rooms below a certain size threshold and create a bi-directional graph for the remaining rooms, computing the distance between each pair. Using this graph, the rooms are connected either using Kruskal's or a variation of travelling salesman--the latter only when there are fewer than 11 rooms. Next, level generation finds the 'best level path' (essentially just the longest level path between two corners of the level grid), draws our level start and finish tunnels and places styled tiles using marching squares.

With the level's shape determined, level generation places the remaining game assets: enemies, static hazards, gas vents and other interaction zones. This is done iteratively over 5 consecutive passes with different asset placer classes to encapsulate the different types of objects that they place. One of the most interesting passes is dead-end asset placement, which uses A* pathfinding to find all the dead ends in our levels and place dead end interaction zones and gas vents to help the player if they get lost. Finally, we add our parallax background and the level is complete!

Level generation takes anywhere from 0.5-5s (and even longer on older hardware), so it is necessary to run it in parallel with our core game loop. The process is triggered once a player reaches the end a level, and is performed on a separate thread so that we can fade out smoothly and display a loading animation. I discovered c++ promises while building this system, which was a convenient way to transfer level data from the generation thread back to main.

Audio system and sound design

Balloonium includes a configurable audio system for triggering a variety of different sound effects and music. The system handles directional audio and passively-triggered ambient sound effects. It also offers random sample cycling and multi-voice one shot playback for groups of samples. Sound effects consist of home-recorded foley (spider and balloon), software synthesizers (used for fairy lights and checkpoints) and downloaded samples from freesound.org. All sound effects were edited and mixed in ableton live 10. The music is my own original work, also produced with ableton.

The following video demonstrates many of the game's sound interactions with the player.

The level checkpoint sound and particle effect is one of my favourites.

I am a software engineer, game dev and sound designer born and raised in Vancouver, BC.

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