Halo Tweak Guide
[Page 7] In-Game Settings (Pt.3)
Decals: these are the marks left on surfaces such as bullet holes, scorch marks and blood. The more gunfire hits enemies and various surfaces, the more decals will be generated, and although they are eventually faded out, the sheer number of decals on the screen at one time can reduce your performance somewhat. If you want to improve performance, especially in big fight scenes or when online with a lot of players, set this to No, though it will diminish the atmosphere of the game somewhat.
Particles: these effects are the basis of explosions, steam, smoke, sparks and weapons fire among other things. The choices for this setting are Off, Low and High. With particles effects set to Off, you will get a performance improvement however the game will look very unrealistic. The most noticeable impact is on weapons fire which will be non existent. When set to Low, some particle effects are generated, but again the look is not very realistic. However if you need the performance boost, Low is a reasonable compromise. High is recommended for total immersion in the game although it impacts on performance especially during heavy fighting.
Texture Quality: textures are the images which cover every surface. For example the grass on the ground is a texture, as are the walls, floors and sky. The three levels for texture quality - Low, Medium and High - determine how realistic and detailed these textures look. The higher the texture quality setting, the greater the impact on your performance, particularly if you have an older 32MB or 64MB graphics card. Given that some of the textures in Halo are relatively poor quality as they were ported over from the console version, I would recommend at least the Medium setting for most people. If you have a high end graphics card set textures to High for a minimal performance hit.
Gamma: use this setting to adjust the brightness of the Halo game image. It has no impact on performance, and can be adjusted to taste.
Connection Type: set this to the type of Internet connection you have on your PC. If you don't know the name or type of your connection, or don't see it listed here, check your upload speed with your ISP (in kbps) and match it as follows:
56K - 28kbps to 56kpbs
DSL/Cable (Low) - 128kbps
DSL/Cable (Avg) - 368kbps
DSL/Cable (High) - 512kbps
T1/LAN - 768kpbs
Choosing the wrong connection speed, particularly if you choose one higher than your existing connection, can give you a great deal of "lag" in online gameplay.
Server Port, Client Port: you can enter the port number for the client or server, however if you don't know what a Port is or aren't given specific instructions to change these numbers by the server administrator, leave them at default.
Lets you select the color of your character in Multiplayer matches only. Does not affect the color of the player in the singleplayer Campaign mode, and has no effect on performance.
Shows the current build number of your Halo game. Useful for seeing which version Halo has been patched to.
The next section goes into more detail about Advanced Tweaking for Halo.