This case study is written by the Devhouse team, the developers behind SpongeBob Party, a mobile-first social party experience built entirely in UEFN. Our goal in sharing this work is to provide practical lessons for creators interested in building character-driven, persistent experiences with mobile as the primary platform.
When we began development on SpongeBob Party, the objective was to understand what a fully mobile-first UEFN project could look like. Working with Epic Games and Paramount, our team set out to create a character-driven party simulation that fit naturally within the SpongeBob universe while respecting the limitations of mobile hardware and touch-only controls.
Our guiding principle was simple. If a feature did not work well on mobile, it did not make it into the game. This rule shaped nearly every system, from camera behavior to interaction patterns.
Before diving into the full breakdown, here are the most important lessons we learned -
Key Takeaways for Mobile-First UEFN Development
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Design UI for touch first, not as a scaled-down PC interface
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Use Mobile Preview early to catch layout, readability, and performance issues
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Limit entity counts and spread out spawning to maintain performance
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Prefer shorter, focused gameplay loops over complex decision trees
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Use Verse Fields to drive responsive UI without heavy logic
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Leverage Scene Graph for dynamic interactions instead of per-frame checks
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Plan early for mobile-specific lighting and material limitations
Project Overview
Players arrive in a vibrant cul-de-sac where they can claim a plot, decorate it, attract familiar SpongeBob characters, and participate in timed island-wide events. Everything from UI layout to player flow was rebuilt around mobile clarity and responsiveness. The final experience blends customization, simulation, and lighthearted social play in a format that supports both short sessions and long-term progression.
Core Game Design
Three main systems work together to create the rhythm of SpongeBob Party.
Guests
Characters from the SpongeBob universe drive progression. Each guest has defined personality attributes such as Bookish, Cranky, Elegant, Energetic, and Wacky. These traits influence where characters appear, what they respond to, and how they behave throughout the cul-de-sac. Guests move through the space, inspect decor, interact socially, make requests, and reward players when they are satisfied.
Party Customization
Decor is the foundation of progression. Items contribute attribute values that influence guest behavior and availability. As players fill their plots with decor that aligns with different personalities, they unlock additional characters and increase overall party activity. All decor is persistent, which reinforces player ownership and gives the world a lived-in feel.
Events
To break up the slower life simulation loop, we added hourly cooperative events inspired by iconic SpongeBob moments. Examples include feeding the Alaskan Bullworm and confronting the Flying Dutchman. These events give every player on the island a shared objective and introduce larger set pieces that add variety and energy.
Guests: Technical Approach
Supporting a high volume of runtime characters was one of the most demanding technical tasks in the project.
Dynamic Spawning
Early in development, spawning guests with custom runtime parameters required careful sequencing and additional bookkeeping in Verse. As Verse APIs and NPC spawning workflows matured, we refactored the system to take advantage of newer functionality, which significantly improved reliability and reduced setup complexity. The result was a more stable and maintainable spawning pipeline that scaled cleanly as player progression increased.
Conversations
The built-in Conversation Device was not designed for large numbers of dynamically spawned characters, so we moved to a Scene Graph based approach. Each guest receives a dynamic interaction zone that updates based on its current state, allowing conversations to branch according to mood, needs, and context.
During one UEFN update cycle, interactable components temporarily stopped behaving as expected. Epic was already aware of the issue, and our feedback from SpongeBob Party helped validate the impact at scale. In the interim, we tied conversations to Input Triggers with manual proximity checks and added clear visual cues so players could still interact reliably until the issue was resolved.
Offline Behavior
Guests persist between play sessions. Their needs advance slowly while players are offline, which keeps the simulation active without overwhelming returning players. Guests who are left unattended for too long may leave the party, adding personality to the system while preventing unattended resource accumulation.
Party Customization: Technical Approach
Decor placement went through more iteration than any other feature.
Initial Prototype
Our first prototype used a socket-based grid tied to first-person placement. While functional, the number of sockets required across curved plots introduced performance instability and visual clutter. On mobile devices, the system felt noisy and difficult to control.
Final System
We transitioned to a grid-free, RTS-style camera system. Using UEFN’s Fixed Angle Camera Device and a hidden ghost prop as the camera target, players move the focus point directly instead of repositioning their character. This created a clean top-down editing mode that translated well to touch input.
On mobile, a single virtual stick controls the ghost, while the selected decor item remains centered and unobstructed. This approach proved reliable across all performance profiles and was easier for new players to understand.
Shops and Consumables
The shop system rotates inventory on a global schedule, with synchronized stock across all players. Purchases flow into persistent storage. Consumables integrate with UEFN carryables while still participating in placement logic when thrown, allowing them to function in both party spaces and events.
Events: Technical Approach
Events were designed to be visually impactful while remaining structurally lightweight. They rely on a combination of Creative Props, Scene Graph entities, and custom logic.
The Alaskan Bullworm event uses sequencers for animation timing, entity logic for hit validation, and custom eat-zones that detect thrown food. The Flying Dutchman follows a similar structure with its own animations and interaction loops. Each event awards themed rewards and provides a change of pace before players return to managing their plots.
Outcome
SpongeBob Party pushed our team to rethink how persistent systems, character interactions, and UI should be structured when mobile is treated as the primary platform. Many of the solutions developed for this project now inform our broader approach to UEFN design.
Player feedback has been especially valuable in refining pacing, UI clarity, and event frequency. As new UEFN features continue to roll out, we are actively evaluating how they can further improve character behavior, interaction depth, and mobile performance.
SpongeBob Party is designed as a living experience, with plans to introduce additional content, events, and characters over time. Our hope is that this case study helps other creators approach mobile-first UEFN development with clearer expectations and practical strategies grounded in real production experience.