Eco-Bastion: Pyrolysis Defense

While climate anxiety is a pressing reality, environmental gaming often suffers from being overly academic or passive. My goal was to take pyrolysis—the scientific process of chemically decomposing waste into green energy in an oxygen-free environment—and reimagining it as a high-octane, cooperative VR adventure. By leveraging Meta Horizon, we transformed a complex ecological concept into a physical, tactile team sport, making the act of environmental restoration feel as dynamic and urgent as a classic arcade shooter.

What it does

Eco Bastion: Pyrolysis Defense is a co-op social tower defense game where players physically clean up a virtual ecosystem and run real-time chemical refining processes to fight back pollution.

• Players must harvest plastic pollution, invasive overgrowth, and timber, then sort them into specialized Pyrolysis Reactors.
• Inside the reactor, players must manually balance heat (400^\circ\text{C}–600^\circ\text{C}) and pump out oxygen to create a vacuum.
• Successfully doing so yields Biochar to heal the land and build barricades, and Syngas/Bio-oil to fuel elemental defensive turrets.
• Opening the hatch early introduces oxygen, causing a backfire that burns your hard work into useless ash!

🛠️ How we built it

The project is built entirely for standalone VR running on Horizon OS, optimized for Meta Quest hardware using a mobile-forward architecture.

• Core Logic: Written using JavaScript/TypeScript behaviors native to the Meta Horizon Worlds creation framework.
• Thermodynamic Engine: Built a custom deterministic state script that calculates real-time chemical yield outputs (T, P, O_2 variables) based on the exact material ratios players feed into the machine.
• Performance Optimization: Because standalone VR demands a locked 72Hz/90Hz refresh rate, we bypassed heavy dynamic lighting. Instead, we used a low-poly Solarpunk asset kit relying on emissive, unlit mobile shaders to let the glowing reactor pipes visually communicate system statuses without destroying the frame rate.
• Audio & Avatars: Fully integrated the Meta Horizon Avatar SDK and Meta Spatial Audio, ensuring players can accurately hear a pressure leak behind them in 3D space.

Challenges we ran into

• Network Syncing vs. VR Latency: In a fast-paced co-op game, if a player picks up a piece of debris and experiences even 100ms of lag, it causes motion sickness. We solved this by implementing Client-Side Authoritative Physics—the moment your hand grabs an item, your headset takes local ownership of its physics node, while the global reactor gauges remain synchronized on a separate host heartbeat.
• Teaching Complex Chemistry in 30 Seconds: Pyrolysis sounds intimidating to casual gamers. Our first prototype had too many floating text boxes. We threw them out and went 100% diegetic (in-world). We replaced text with mechanical dials, colored LED safety bands, and physical levers. If a gauge goes into the red, it looks and sounds like a boiling boiler, making the science instantly intuitive through spatial design.

Accomplishments that we're proud of

• Creating True Social Interdependence: Watching playtesters naturally split into roles—one person frantically shouting "I need more plastic for Syngas!" while another is pumping the bellows to drop the oxygen levels—proved that the physical co-op loop truly clicked.
• Perfect Framerate Stability: We successfully managed a chaotic wave of sludge enemies, multiple active reactors, and particle vapor systems on a mobile VR chipset without a single frame drop, maintaining a comfortable, crisp experience.

What we learned

• **Prioritize Tactile Friction over Automation: Unlike traditional flat-screen gaming where seamless automation is the goal, VR users crave physical engagement. We discovered that players find it much more rewarding to manually operate levers and valves; by making the reactor mechanics slightly unpredictable, we increased the fun through haptic resistance and manual labor. Spatial Audio as a Functional Mechanic: Audio feedback in a 3D space—such as the specific hiss of a valve or the thrum of a successful burn—proved more efficient than visual UI for guiding player actions. These spatial cues allow for faster behavioral shifts within the immersive environment.

What's next for Eco Bastion

• **Persistent Meta-Loop: The Community Greenhouse: To foster long-term engagement, we plan to link match rewards to a permanent social lobby within Horizon Worlds. By pooling surplus Biochar earned in-game into a collective greenhouse, the community can collaborate to cultivate real-time blooming gardens and expand shared social environments. ● Evolving Ecosystems: We are developing seasonal biomes, such as the "Sunken Mangrove," featuring dynamic environmental hazards like rising tides. These events will periodically submerge lower-level reactors, challenging teams to reconfigure their piping systems on the fly.

Built With

• meta-avatar-sdk
• visual-audio-framework