Halo: Combat Evolved, also known as Halo 1, is the first installment of the Halo game series. It was created by Bungie and initially released on the original Xbox in 2001 by publisher/owner Microsoft. In 2003, the game was released for Windows PC and Mac via different studios.

Halo 1 uses Bungie's proprietary Blam! engine, which also formed the basis of later games in the series. PC versions of the game support a variety of command line/shortcut arguments to configure and toggle features.

Modding

Today, most modding of H1 is focused on H1A MCC and Halo Custom Edition. Regardless of the target engine, the recommended approach is to use the MCC mod tools for tag authoring and optionally invader to extract tags and build maps for other targets.

Editions and versions

Xbox (Bungie, 2001)

Sometimes called h1x or OG Xbox, this is the classic first release of Halo 1 for the original Xbox. It supports LAN multiplayer and spawned a competitive community which is still active. While original Xbox consoles are hard to come by, emulation is an emerging alternative. Though it is a more involved process, custom maps created with the HEK can be ported back to Xbox.

Xbox has a rich history of modding, notably:

• Halo 1.5, which adds new competitive maps. Custom edition ports of these maps are also available
• Halo 1 Final, and its Neutral Host Edition (NHE), is a newer competitive mod with modified sounds, time callouts, and a selection of stock and H1.5 2v2-oriented maps
• Patch Edition (PE) is a modified version of NHE with map adjustments by Patch and hirsute.

Halo PC (Gearbox Software, 2003)

Often called retail or PC, this edition is the classic port of Halo 1 to Windows PC by developer Gearbox Software and publisher Microsoft Game Studios. Compared to the Xbox version, the PC port included a number of changes (for better and worse):

• Modification of some multiplayer maps' level geometry
• Addition of server browser and online play
• Addition of Banshees to multiplayer
• Addition of the flame thrower, fuel rod gun, and rocket warthog
• Addition of the multiplayer maps Death Island, Ice Fields, Gephyrophobia, Infinity, Timberland, and Danger Canyon
• Addition of a dedicated server, haloceded.exe
• The model tag was modified into gbxmodel
• A new "jet" particle creation physics type was added to the particle_system tag
• Regressions in visuals and assets due to platform differences and the port being based on a pre-release version of Xbox Halo 1

The game received several patches since its release to address remote exploits, remove the CD requirement, replace the GameSpy Arcade lobby, and other minor improvements. Its current version is 1.0.10 ([2014][patch]).

Several beta versions of Halo PC can also be found online. Beta 1.5 has unfinished versions of PC-exclusive content and weapon tuning similar to pre-release Xbox versions. Marketing beta 1.8 features doppler and a model detail option.

Custom Edition (PC, Gearbox Software, 2004)

Custom Edition is a standalone version of Halo PC released in 2004 which supports custom multiplayer and singleplayer maps created using the HEK. It does not include the stock campaign.

Mac (Westlake Interactive, 2003)

The Gearbox PC port (retail) was itself ported to Mac by Westlake Interactive and published by MacSoft. No significant changes were made aside from platform compatibility, and maps are byte-for-byte identical to retail's. With MacSoft's shutdown in 2011, this version has not been receiving the latest patches. Nil's fix enables its continued use with intel GPUs on OSX Mavericks and the post-Gamespy lobby master server.

The Mac edition has a mod called Halo Mini Demo, or HaloMD, which allows it to be played on modern systems. The plugin Halo+ by Samuco can be used to enhance to experience, and a netcode translator can be used to connect to Custom Editions servers.

Demo (PC and Mac)

The free demo versions of Halo 1 on Mac and PC include just the multiplayer map Blood Gulch and the campaign mission The Silent Cartographer (b30). Upon closing the demo, players are presented with the iconic Sergeant Johnson advertisement (demo.bik).

Anniversary (Xbox 360, 343 Industries, 2011)

In 2011, Halo: Combat Evolved Anniversary was released for Xbox 360. Often called CEA or H1A. It was developed by 343 Industries and Saber Interactive as a remaster of the original Halo: Combat Evolved, and is derived from the Gearbox PC port.

This edition introduced the ability to switch between classic and remastered/anniversary visuals and sounds with the press of a button, using the secondary Saber3D engine and assets alongside Halo's classic renderer.

MCC (PC and Xbox One, 343 Industries, 2014-2021)

CEA was ported to PC and Xbox One too as a part of Halo: The Master Chief collection (MCC), again maintained by 343i and Saber. MCC uses Unreal Engine as a menu and input layer over the respective engines of each included Halo game.

Custom maps can be created for MCC PC using its official mod tools. Invader also supports building H1A maps from tags. Mods for the Saber3D content are unsupported. Users must turn EAC off to play custom maps in multiplayer.

This branch of the H1 engine is certainly the "most advanced" and definitive. It contains hundreds of bug fixes, extends limits, cleans up deprecated tag fields and script functions, incorporates code from Custom Edition and later Halo games, and adds new modding capabilities (even some from OpenSauce).

With the introduction of the Saber3d engine also came new file formats:

• The ipak holds all the texture information for the game. This includes classic textures as well.
• The imeta holds entries for the ipak. This links textures in the ipak to the level.
• The fmeta is designed to link dependent files together.
• The s3dpak is an archive file holding the files needed for the Saber engine.

There are some differences between the PC/MCC and Xbox 360 versions; most of the assets have been rearranged to optimize things for their respective platforms.

• Xbox uses a different compression algorithm. The chunking is still done the same; however, it does not utilize zlib.
• Xbox does not utilize ipak/imeta/fmeta. Instead the primary filetype is the s3dpak.

Acknowledgements

Thanks to the following individuals for their research or contributions to this topic:

• gbMichelle (H1A/MCC lineage information)
• Hasuku (Xbox modding lineage)
• Kavawuvi (Engine versions, H1A BSP data base address)
• Neo (Providing the marketing beta)
• Vaporeon (Analyzing marketing beta)
• zatarita (Documenting H1A differences from PC and between versions, summarizing new formats)