FortBox | Devpost

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What is FortBox?

FortBox is a competitive 1v1 building battle game on Roblox featuring Fortnite-style mechanics - grid-based building, turbo placement, material management, ranked matchmaking, and AI-powered coaching.

Play Here!

https://www.roblox.com/games/103903599302811/Swamp-Duels#!/about

Challenges

Challenge	Integration
Best Game Design	4 piece types, 3 materials, turbo building, edit system, ranked ELO
Best Creative Media	Screen shake, damage flash, victory cinematics, 13 voice clips
Best User Design	5 colorblind modes, UI scaling, reduced motion, subtitles
Gemini API	AI coach analyzes stats and gives personalized post-match tips
DigitalOcean	Express API on App Platform with auto-deploy and SSL
ElevenLabs	Voice commentary for eliminations, headshots, victories
MongoDB Atlas	Player data, leaderboard hosting, ELO system
GitHub "Ship It"	Actions CI, Issues, 200+ Commits

Inspiration

We've spent countless hours in Fortnite creative mode back in highschool, perfecting build battles, the rapid wall placements, quick edits, and high-ground retakes. The skill ceiling is what makes it addictive. But we noticed something: the Roblox platform has 150+ million daily users, yet no game truly captures that competitive building experience.

Games like RIVALS showed us that 1v1 duels work incredibly well on Roblox. We wanted to combine that format with authentic Fortnite-style building mechanics, grid snapping, turbo building, material management, and the satisfying edit system that rewards mechanical skill.

Our goal: make competitive build battles accessible to millions of Roblox players while maintaining the depth that makes the genre so rewarding.

*** this idea is novel and has never been done before ***

What it does

FortBox is a competitive 1v1 building battle game featuring:

Core Gameplay

Authentic building system - Grid-based placement (12×12×12 studs) with walls, floors, ramps, and pyramids
Three material types - Wood (150 HP, fast), Stone (400 HP, medium), Metal (600 HP, slow)
Edit system - Modify structures with windows, doors, arches, and directional changes
Turbo building - Hold to place continuously at 0.05s intervals

Competitive Features

Ranked matchmaking - ELO-based rating system (Bronze -> Silver -> Gold -> Platinum -> Diamond -> Champion)
Round-based combat - Best-of-3 elimination rounds
Global leaderboard - See where you rank against all players worldwide
Match history - Track your wins, losses, and improvement over time

AI-Powered Features

Smart coaching - Post-match tips powered by Google Gemini that analyze your kills, deaths, builds, and accuracy to give personalized advice
Voice announcements - Dynamic match commentary ("Elimination!", "Headshot!", "Victory Royale!") using ElevenLabs AI voices

Accessibility

5 colorblind modes - Deuteranopia, Protanopia, Tritanopia, Monochromacy, High Contrast
UI scaling - Adjustable interface size (0.75x to 1.5x)
Reduced motion - Disable screen shake and flash effects
Subtitles - Text display for all voice announcements

How we built it

Game Architecture

We implemented a client-predictive model for building that feels instant while remaining server-authoritative:

Player presses build key Show ghost preview Click to place Optimistically occupy grid -> Validate request

Grid available?
Has materials?
In range (3x3x3)?

Receive confirmation -> Spawn piece, replicate or rollback if rejected

This gives sub-100ms perceived latency while preventing exploits.

Grid System

Every building piece snaps to a uniform 12x12x12 stud grid. Each cell tracks:

Slot occupancy - Which piece types exist (wall, floor, ramp can coexist)
Owner ID - Who placed it (for editing permissions)
Support graph - Structural connections for collapse physics

Backend Infrastructure

We built a Node.js/Express API hosted on DigitalOcean App Platform:

Endpoint	Service	Purpose
`POST /api/match-result`	MongoDB Atlas	Record match outcomes
`GET /api/leaderboard`	MongoDB Atlas	Fetch top 50 players
`GET /api/player/:id`	MongoDB Atlas	Player stats lookup
`POST /api/match-tips`	Gemini API	AI coaching analysis
`GET /api/voice-manifest`	ElevenLabs	Voice clip metadata