If you are diving into Halo PC or Custom Edition modding, you will quickly encounter the need to manipulate game behavior directly in memory. Whether you are creating advanced scripts, building tools, or just experimenting, understanding memory addresses and offsets is a foundational skill.

This guide explains what offsets are, why they matter, and how you can find them using popular tools like Cheat Engine, IDA Pro, and Halo Map Tools 3.

What Are Memory Addresses and Offsets?

  • Memory Address: A specific location in the game’s memory where a piece of data (like player health, ammo, or position) is stored.
  • Offset: A number added to a base address to reach a particular data point.

For example, if a base address is 0x40440000 and the offset is 0x28, the target address becomes:

0x40440000 + 0x28 = 0x40440028

In many modding scenarios, you will not know the absolute address ahead of time because it changes between game sessions. Instead, you find a stable base address (like a module handle) and then apply offsets to reach the data you care about.

For a deeper technical dive, check out Kavawuvi’s post on OpenCarnage about Halo map file structures.

Why This Matters for Halo Modding

Memory offsets let you:

  • Read and modify player stats in real time.
  • Create custom gameplay mechanics (e.g., infinite ammo, health regeneration).
  • Debug and analyze game behavior.
  • Build external tools or scripts (like Sapphire Lua scripts) that interact with the game.

Without offsets, you would be guessing where data lives. With them, you gain precise control.

Tools for Finding Offsets

Here are three tools commonly used in the Halo PC/CE modding community:

  • Cheat Engine
    A powerful, real-time memory scanner and modifier. Great for beginners and advanced users alike.

  • IDA Pro
    A professional disassembler and debugger. Useful for reverse engineering the Halo executable itself.

  • Halo Map Tools 3
    A utility designed specifically for Halo. It simplifies finding and modifying offsets within map files.

Tutorials and Resources

To get started with finding and using offsets, explore these resources:

Practical Tips for Success

Follow these steps to find offsets efficiently:

1. Start with Known Values

Pick a value you can easily change in the game, such as:

  • Current health
  • Ammo count
  • Shield strength

Search for that value in Cheat Engine.

2. Use Cheat Engine’s Scanning Features

  • First Scan: Enter the known value and perform an initial scan.
  • Next Scan: Change the value in the game (e.g., take damage, fire a weapon), then scan for the new value.
  • Repeat until you have a small list of candidate addresses.

Pro Tip: Use exact value scans when possible. If the value is displayed as a number in the game (like 100 health), scan as 4-byte integer.

3. Verify the Address

Once you have a candidate address, change it in Cheat Engine and see if the game reflects the change. If it works, you have found the dynamic address.

4. Pointer Scanning

Dynamic addresses change each time you restart the game. To find a stable base address and offset chain:

  • Right-click the working address in Cheat Engine.
  • Select “Pointer scan for this address”.
  • Configure the scan settings (maximum offset depth, address range).
  • Restart the game and compare pointer results to find a consistent chain.

Warning: Pointer scanning can generate thousands of results. Be patient and filter by reloading the game a few times to see which pointers survive.

5. Document Your Offsets

Keep a list of discovered offsets, their data types, and what they control. This saves time in future projects.