Proof of Concept Demo (October 2025)

🚧 Historical Archive: This PoC demonstrates initial feasibility. Not production-ready.

Overview

A vertical slice from scratch in under 20 days: Started with Unity, then ported to Godot (no XP) and Unreal (no XP) in 3 days each.

^{Watch the video on YouTube (1:20)}

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🧐This can’t possibly work!!🤥

It does!

It’s really not rocket science: Engines aren’t that different. They all make games using the same basic set of high-level features. LunyScript aims to standardize only that high-level functionality. Because these features are so fundamental, they don’t change at all.

I asked a provocative question on reddit and a follow-up and the responses were uniformly:

• It’s impossible ⛔
• Makes no sense 😐
• Nodody needs this 🗑️
• APIs are easy anyway 🙂‍↔️
• It’s a massive amount of work 😫
• The point of engines is to be different 🤔

I call this cognitive bias, and my fault: I did not explain it as well as I can now. Also: wrong audience.

So, How Does It Work?

→ How LunyScript unifies different engine architectures
→ API design philosophy and principles
→ Code comparison: LunyScript vs Engine scrips
→ More Design details
Note: Physics behaviour will deviate between physics engines, requires scaling values.

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What’s Implemented

The PoC demonstrates LunyScript orchestrating essential gameplay systems across all three engines:

System	Features Demonstrated
Input	Keyboard input detection
Physics	Rigidbody movement, forces, velocity control
Collision	Collision detection events, collision filtering
Assets	Prefab addressing, instantiation
Scene Graph	Object create/destroy, find children by name, transform
UI	Text display, Variable binding, Button press events
Variables	Game state and progression, timer & score
Audio	Sound effect playback

Scope: High-level gameplay scripting - orchestrating game logic, behaviors, and interactions. LunyScript is not a game engine API replacement.

Learnings

LunyScript will have a different architecture in key aspects:

• Single script runner: Orchestrates LunyScripts on any engine type (PoC: one runner per engine type => subclass explosion)
• Engine-agnostic scripts: Scripts subclass ´LunyScript´ type to avoid leaking engine artifacts
• Asset convention: Only assets in ‘Luny’ folder(s) will be accessible by string
• Unreal deferred: It’s not a beginner-friendly engine, and C# isn’t the native experience

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Media

Godot

Unity

Unreal

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Source Code Repositories

Repos need to be cloned recursively: git clone --recursive ...

Engine	Repository
Godot	LunyScratch_Examples_Godot
Unity	LunyScratch_Examples_Unity
Unreal	LunyScratch_Examples_Unreal

^{Note: I can’t guarantee that these projects will open and run without errors for everyone. I will not maintain them.}

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Example: Player Controller Script

This is the script for the “Police Car” which acts as both player controller and overall game state.

⚠️ Note: API in this PoC represents an early first draft. Final API will differ in key aspects. It will not leak engine details into the script.

using Godot;
using LunyScratch;
using System;
using static LunyScratch.Blocks;
using Key = LunyScratch.Key;

public sealed partial class PoliceCarScratch : ScratchRigidbody3D
{
    [Export] private Single _turnSpeed = 70f;
    [Export] private Single _moveSpeed = 16f;
    [Export] private Single _deceleration = 0.85f;
    [Export] private Int32 _startTimeInSeconds = 5;

    protected override void OnScratchReady()
    {
        var progressVar = GlobalVariables["Progress"];
        var scoreVariable = Variables.Set("Score", 0);
        var timeVariable = Variables.Set("Time", _startTimeInSeconds);

        // Handle UI State
        HUD.BindVariable(scoreVariable);
        HUD.BindVariable(timeVariable);

        Run(HideMenu(), ShowHUD());
        RepeatForever(If(IsKeyJustPressed(Key.Escape), ShowMenu()));

        // must run globally because we Disable() the car and thus all object sequences will stop updating
        Scratch.When(ButtonClicked("TryAgain"), ReloadCurrentScene());
        Scratch.When(ButtonClicked("Quit"), QuitApplication());

        // tick down time, and eventually game over
        RepeatForever(Wait(1), DecrementVariable("Time"),
            If(IsVariableLessOrEqual(timeVariable, 0),
                ShowMenu(), SetCameraTrackingTarget(null), Wait(0.5), DisableComponent()));

        // Use RepeatForeverPhysics for physics-based movement
        var enableBrakeLights = Sequence(Enable("BrakeLight1"), Enable("BrakeLight2"));
        var disableBrakeLights = Sequence(Disable("BrakeLight1"), Disable("BrakeLight2"));
        RepeatForeverPhysics(
            // Forward/Backward movement
            If(IsKeyPressed(Key.W),
                    MoveForward(_moveSpeed), disableBrakeLights)
                .Else(If(IsKeyPressed(Key.S),
                        MoveBackward(_moveSpeed), enableBrakeLights)
                    .Else(SlowDownMoving(_deceleration), disableBrakeLights)
                ),

            // Steering
            If(IsCurrentSpeedGreater(0.1),
                If(IsKeyPressed(Key.A), TurnLeft(_turnSpeed)),
                If(IsKeyPressed(Key.D), TurnRight(_turnSpeed)))
        );

        // add score and time on ball collision
        When(CollisionEnter(tag: "CompanionCube"),
            IncrementVariable("Time"),
            // add 'power of three' times the progress to score
            SetVariable(Variables["temp"], progressVar),
            MultiplyVariable(Variables["temp"], progressVar),
            MultiplyVariable(Variables["temp"], progressVar),
            AddVariable(scoreVariable, Variables["temp"]));

        // blinking signal lights
        RepeatForever(
            Enable("RedLight"),
            Wait(0.16),
            Disable("RedLight"),
            Wait(0.12)
        );
        RepeatForever(
            Disable("BlueLight"),
            Wait(0.13),
            Enable("BlueLight"),
            Wait(0.17)
        );

        // Helpers
        // don't play minicube sound too often
        RepeatForever(DecrementVariable(GlobalVariables["MiniCubeSoundTimeout"]));
        // increment progress (score increment) every so often
        RepeatForever(IncrementVariable(progressVar), Wait(15), PlaySound());
    }
}

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