Introduction
Archer Defense is a fast, hyper-casual vertical action game built for Meta Horizon Worlds’ portrait mode, designed from the ground up for true mobile-first play.
Players defend against endless waves of enemies, chase high scores, and jump into chaotic co-op runs — all within short, high-intensity sessions optimised for one-handed mobile interaction. The experience strips away traditional Horizon conventions, including the default avatar system, to deliver gameplay that feels closer to a native mobile title than a typical virtual world.
Developed for SensAI Hack – Barcelona, Archer Defense won First Prize in the Horizon Worlds Category, validating the approach and proving that portrait-mode action in Horizon can be fast, readable, and deeply engaging.
The Challenge
Our goals for Archer Defense were intentionally strict:
- Prove that portrait mode can support true hyper-casual action gameplay.
- Build a Horizon world that feels native to mobile, not adapted from desktop or VR.
- Avoid default avatar mechanics and create fully custom gameplay systems.
- Deliver gameplay that works equally well in solo and co-op multiplayer.
- Maintain clarity, pacing, and readability in a vertical combat space.
The most complex challenge was multiplayer:
while a single-player version was straightforward, making wave-based combat feel fair, readable, and satisfying with multiple players on a small vertical screen required continuous iteration.
Solution
We rebuilt every core system from scratch, designing specifically for portrait-first interaction and fast sessions.
Core Gameplay & Systems
- Endless Wave Combat
Players face increasingly challenging enemy waves, pushing for higher scores while adapting to rising difficulty. - Solo + Co-Op Design
The game dynamically supports both single-player runs and chaotic co-op sessions, with enemy logic and pacing tuned for shared play. - Hyper-Casual Loop
Short runs, immediate feedback, and fast retries reinforce a “just one more run” rhythm.
Custom Mobile-First Architecture
- Custom Camera System
Built specifically for vertical framing, ensuring constant visibility of threats and player actions without visual overload. - Bespoke Input & UI
All interactions and interface elements were designed for portrait orientation, prioritising clarity and responsiveness on mobile screens. - Non-Avatar Gameplay
By bypassing Horizon’s default avatar system, we achieved tighter control over animation, scale, and combat readability.
Visuals, Audio & Polish
- Vertical-Optimised Art & Effects
All visuals, VFX, and audio cues were tuned to reinforce spatial awareness in a tall, narrow playfield. - Performance-Focused Implementation
Systems were engineered to remain smooth and responsive even during intense co-op wave scenarios.
Results
Awards & Recognition
- 🏆 First Prize – Horizon Worlds Category
SensAI Hack – Barcelona (Sponsored by Meta)
Player & Engagement Impact
- Immediate understanding of gameplay within seconds.
- Strong engagement driven by fast runs and competitive scoring.
- Positive feedback on how “mobile-native” the experience feels compared to traditional Horizon worlds.
Technical Wins
- Fully custom gameplay, camera, and UI systems.
- Stable solo and multiplayer performance in portrait mode.
- A reusable foundation for future hyper-casual and action-oriented projects.
Why It Matters
Archer Defense showcases Byten21’s ability to:
- Design mobile-native games on emerging UGC platforms.
- Rethink core systems — camera, UI, pacing — for portrait-first interaction.
- Deliver polished, award-winning gameplay without relying on default platform conventions.
About Byten21
Byten21 is a London-based creative production studio building games and interactive experiences on UGC platforms including Meta Horizon Worlds, Roblox, TikTok, and Snapchat.
We specialise in mobile-first gameplay, custom systems, and performance-optimised multiplayer experiences designed for social play and rapid engagement.
Looking to build a mobile-first game or interactive experience on UGC platforms?
Let’s talk.