S&box (Source 2, C#) Developer – Physics-Based Project (GitHub link check)

I’m looking for a developer to build a physics-based experience in S&box (built on the Source 2 engine, using C# scripting).
https://github.com/Facepunch/sbox-public
The project will be managed using GitHub for version control and collaboration.

Before sharing full details, I’d like to get a rough estimate for scope and cost.

Core Requirements
Create 10–12 custom stylized low-poly 3D models in Blender
Include simple animations (squish, bounce, scale-in, interaction effects)
Implement physics-based object spawning and collision handling using S&box systems
Develop a core interaction/combination mechanic with support for chained outcomes
Deliver polished, responsive gameplay feel
Screen shake
Slow-motion effects
Satisfying feedback
Build a score system
Combo tracking
Personal best
UI implementation:
Score display
Next object preview
Combo indicator
End screen
Design one main stylized environment/scene
Ensure good performance and optimization
Planned Features (Optional / Phase 2)

Depending on budget and timeline:

Multiplayer (1v1 or shared sessions)
Real-time leaderboard
Player progression (XP / levels)
Cosmetic skins
Party / lobby system
Spectator mode
Daily challenges / login streaks
Technical Expectations
Experience with S&box and Source 2 workflow
Strong knowledge of C# scripting
Familiarity with physics-based systems
Ability to integrate Blender assets properly
Comfortable working with GitHub
Next Step

** Answer what is 3x5+1=

Please share:

Portfolio or past work (preferably S&box / Source 2 projects)
Estimated cost range
Estimated timeline