Chimera

Chimera is the update to Halo: Combat Evolved for the PC that we should have had but never got.

It is licensed under version 3.0 of the GNU General Public License. See LICENSE for more information.

The official repository is hosted at https://github.com/SnowyMouse/chimera

Table of contents

• Installation
• Mod support
• Features
• FAQ
• Compilation Guide

Installation

Here is the installation procedure for installing Chimera:

1. Update Halo to version 1.10 (unless you're playing the trial).
2. Back up your game's Strings.dll. Renaming it to strings-old.dll works.
3. Copy strings.dll, chimera.ini, and fonts into your game folder.
4. Optionally add a mods folder to load custom dll mods.

NOTE: Each file goes into the main game folder, NOT controls. If you put the files in controls, it will not work.

Uninstalling Chimera is simple:

1. Delete Chimera's strings.dll and optionally chimera.ini, fonts, and/or mods.
2. Rename your backed up copy of Halo's Strings.dll back to strings.dll.

Mod support

You can install binary mods (i.e. dlls) by creating a folder called "mods" and copying the dlls into the directory.

NOTE: Chimera does not support some dll mods such as HAC2 or Open Sauce. This is because they modify the game in similar ways, resulting in them conflicting with one another. Supporting just one of these mods would mean extra development time that we don't have. Sorry.

Features

Chimera provides a number of features and enhancements to the base Halo game. To ensure the base game is preserved as much as possible, most features are not turned on by default, and the ones that are only exist to enhance or fix the game.

• Passive features
• Custom Edition map support on retail
• Ini features
• Commands

Passive features

These are features that are always on.

• Interpolation
• Limit increase
• Compressed maps
• Campaign in Custom Edition
• Camera shake fix
• Checkpoint fix
• Reduced DRM
• Descope fix
• Extended description fix
• Fast loading
• Fast server listing
• 128 MiB map leak fix
• Model LOD fix
• FOV fix
• Sun fix
• Zoom blur fix
• Multitexture overlay fix
• Z-fighting fix
• Custom chat
• NVIDIA camo fix
• Contrail fix
• Motion sensor fix
• Auto center fix
• Shader fixes
• Texture formats fix
• Fog fix
• Model detail fix
• HUD numbers fix
• Weapon swap ticks fix
• Name fade fix
• Scoreboard fade fix
• Timer offset fix
• Sane default Halo settings
• Removed update check
• Removed Watson
• Multi-team vehicles fix
• Map downloading
• Lua scripting

Interpolation

The game has an issue where object movement is tied to tick rate, thus objects will never move faster than 30 frames per second. Chimera adds interpolation to the game for objects and other effects.

Limit increase

Chimera increases some of the limits of the game. Note that, unless you play a map that exceeds these limits, your performance will not be impacted. If you don't have this on, then maps that exceed the limits will look incorrect and may not even be playable. Therefore, this feature is always on. Here are the increases:

• BSP polygon limit boosted to 32767
• Visible object limit boosted to 1024
• Draw distance increased to 2250 world units (~6.86 km)

Compressed maps

Chimera supports maps compressed with the chimera-compress compression tool. This allows you to take advantage of the blazingly fast zstd compression algorithm, drastically cutting down map size.

If maps in RAM is enabled, compressed maps will be decompressed directly into RAM. Otherwise, temp files will be used (placed in Chimera's folder).

Campaign in Custom Edition

Normally, Halo Custom Edition does not display a "campaign" option on the main menu. If all of the campaign maps are availible in the maps folder, Chimera will reenable the "campaign" option just like in the retail version.

Camera shake fix

Chimera fixes a bug where camera shaking does not work at high frame rates.

Checkpoint fix

Chimera fixes a bug where checkpoints time out too fast at high frame rates.

Reduced DRM

Normally, Halo does not allow you to join servers with someone that has the same CD key. This was done to prevent people from sharing CD keys. However, this protection has shown to not work and, as a result, is purely an hindrance to people who have legitimate copies of the game, such as modders. By disabling the CD key check, you can locally host a game that lets you join yourself. Also, because a large number of players do not own legitimate copies of the game, having the CD key check in place will likely prevent you from getting any players in the first place.

Note that this feature does not "crack" the game. You still need a valid Halo installation in order to run the installer for the game as well as update the game to 1.10.

Descope fix

When you take damage while zoomed in, the game zooms back out automatically. This functionality is broken when in a server, as the client only descopes when the player takes damage on the client instance rather than if they actually took damage on the server. Chimera changes this to making it so if you lose health or shield, you are descoped.

Extended description fix

Chimera fixes a bug where the "About" button of the profile settings menu doesn't display the correct bitmap in the extended description.

Fast loading

Halo Custom Edition CRC32s every map on startup. On a small maps folder, this does not significantly increase loading time. On a massive maps folder, this drastically increases loading time, ranging from seconds to minutes.

Some mods "fix" this by storing the CRC32 in a cache, but this negates the point of it in the first place, as now you can join servers with mismatched CRC32s. Chimera truly fixes it by CRC32ing the map when you load the map, not the game.

Fast server listing

The game takes forever to query the master server. Chimera speeds it up.

128 MiB map leak fix

If you load a map that exceeds 128 MiB, the game opens the map multiple times and only closes it once. This results in the map leaking, and eventually, the game could run out of file descriptors. Chimera fixes this by removing the file size check.

Model LOD fix

The game uses your vertical resolution to determine how detailed to draw a model. However, this results in levels like The Pillar of Autumn showing the highest LOD for some models when it shouldn't, leading to infamous glitches like the "4K headless chief" glitch. Chimera makes it scale by 480p, instead.

FOV fix

There is a bug in the game where, when you increase the vertical resolution of the game, your FOV gets slightly more narrow, even if you are on the same aspect ratio. Chimera fixes this so FOVs stay consistent between vertical resolutions. This does NOT fix low FOV at widescreen aspect ratios, which is what chimera_fov is for.

Sun fix

Lens flares are drawn at a set number of pixels regardless of vertical resolution. Chimera makes it scale by 768p, instead.

Zoom blur fix

The zoom blur radius is a set number of pixels regardless of vertical resolution. Chimera makes it scale by 480p, instead. Chimera also increases the resolution of the zoom blur effect, improving the quality.

Multitexture overlay fix

Chimera fixes an issue where multitexture overlays in weapon_hud_interface tags do not blend correctly (notably the sniper rifle angle ticks).

Z-fighting fix

The game has an issue where as the player gets further from the center of a map, Z-fighting gets progressively worse due to loss of floating point precision. Chimera attempts to reduce decals Z-fighting with level geometry.

Custom chat

The Keystone chat is crashy and broken. Chimera adds a replacement chat.

NVIDIA camo fix

Chimera fixes a bug where, if the GPU is an NVIDIA graphics card, it uses alpha blended camo instead of the liquid camo shader. This is only applicable to Halo Trial.

Contrail fix

Chimera fixes a bug where contrails are bugged at high frame rates.

Motion sensor fix

Chimera fixes a bug where the motion sensor fade is incorrect at >30 FPS

Shader fixes

Chimera fixes many gearbox shader regression to restore Xbox accurate rendering. This includes missing shader types such as shader_transparent_generic.

Texture formats fix

Chimera restores support for the monochrome and p8-bump texture formats used in the Xbox version.

Fog fix

Fog in maps such as Assault on the Control Room's sky fog now works as intended.

Model detail fix

The "detail after reflection" flag in model shaders now works as intended.

HUD numbers fix

HUD numbers are no longer drawn oversized if modified to be a higher resolution.

Weapon swap ticks fix

Weapons are now picked up with the correct timing when holding the action key.

Auto center fix

Chimera fixes a bug where the game does auto look centering based on frame rate. This would result in vehicles being difficult to handle at high frame rates.

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