name: openclaw description: Use this skill when working with the OpenClaw game engine or its Lua scripting systems. Triggers when modifying engine source code, Lua scripts, or asset configurations.

OpenClaw

What this is

OpenClaw is an open-source, cross-platform re-implementation of the engine used in the 1997 platformer game "Claw". It is written in C++ and leverages SDL2 to ensure compatibility with modern operating systems while introducing advanced features like Lua scripting for object logic.

Installation

git clone https://github.com/OpenClaw/OpenClaw.git
mkdir build && cd build
cmake ..
make
# Note: Requires original CLAW.REZ file in the execution directory

Key concepts

• REZ Archive: The engine uses a virtual file system to read assets from original .REZ containers. You do not need to extract these files; the engine accesses them directly via internal paths.
• Lua Logic: Unlike the original game, OpenClaw uses Lua for level logic and object behaviors. This allows for runtime modification of enemy AI and interactive elements.
• WAP Maps: Level layouts are stored in .WAP files, which define tile layers, object placement, and logic triggers.
• SDL2 Rendering: The engine utilizes SDL2 for hardware-accelerated rendering, allowing for windowed modes and modern resolution scaling.

Correct usage patterns

• Lua Scripting for Objects: When defining a new object behavior in a Lua script:

  -- Example: A custom health pickup script
  function OnTouch(player, object)
      if player:GetHealth() < 100 then
          player:AddHealth(10)
          object:Destroy()
          PlaySound("GAME_GETHEALTH")
      end
  end
  

• Configuring the Engine: Adjusting settings via config.xml:

  <config>
      <video width="800" height="600" fullscreen="false" vsync="true" />
      <game path="./CLAW.REZ" />
  </config>
  

Common mistakes to avoid

• Case Sensitivity: Linux builds are case-sensitive. Ensure that asset paths requested in code match the case inside the .REZ file (e.g., IMAGES/LEVEL1.PCX vs images/level1.pcx).
• Missing Original Assets: OpenClaw is an engine only. It will fail to launch without the original CLAW.REZ file from the 1997 retail game.
• Lua Syntax: Ensure scripts follow the specific Lua version embedded (typically Lua 5.3). Avoid using platform-specific OS calls within Lua scripts to maintain cross-platform compatibility.

File and folder conventions

• /src: Contains the C++ source code for the engine core and rendering logic.
• /scripts: Directory for Lua-based object behaviors and level logic.
• /assets: Location for external configuration files and non-REZ media.
• config.xml: The primary configuration file for engine behavior and asset paths.