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This guide is primarily for Single-Player gaming. Performance will always be compromised to a certain degree(see two sections above).

I know some will invariably come up with two separate configs - one for single-play and another for on-line.You do that because,when you're on-line, visuals really take a backseat. However, there is one very important thing to consider when you do that. And it has to do with mixing single-play and multiplay gaming sessions randomly. 

Instead of me trying to explain the problem anyone will encounter with having two separate configs, here's an e-mail below(text in this color)I sent to Mad Dog regarding my concern (slightly changed and edited) :

__________________________________________________________________

Hi, just only managed to actually finish going thru' your M+K configs for Half-Life.
An important thing to consider:

setSP.cfg & setDM.cfg
=================

I noticed that in setDM.cfg relative to setSP.cfg,you've:

1)increased both brightness and gamma
2)increased the value of texgamma and reduced the value of lightgamma

This is all fine and I absolutely understand why this is so but I don't think
you understand the consequence of this in terms of people(like you and me)
who switches back and forth between SP and DM in every gaming session.
I have only just discovered this myself,in fact.

There are many permutations as to how a person plays H-L.Gaming sessions
could go like this:

1)SP then DM then SP then DM then SP (i.e. a consistent pattern); or
2)SP,SP,DM,SP,DM,DM,SP (i.e. not consistent and a pretty much random
pattern)

The thing about H-L(and other games) in terms of configuring for SP and
DM is the fact that best visuals don't equate best performance.That's to
be expected.But the damnest thing about H-L is the fact that some
settings(specifically brightness,gamma,texgamma and lightgamma since
they have the most impact in terms of visuals) don't take effect in its entirety
unless you restart after making changes in-game.Whenever you make
changes to these values in-game, they're written to the relevant
Windows registry path and value in real-time. BUT in-game visuals
don't change - except for weapons and models but not everything
else(textures)- during the same session.This is the same thing as if you
have different settings for SP and DM in different configs(like my
config and yours do) that you start the game with,specifying the game to
exec the cfg on the command line and again in-game.

So,say you play an SP session with brightness 1 (the other 3 cvars can be
used as an example too) already written within the registry.The game
will effect that brightness setting game-wide.The setSP.cfg also has the
same specific value.No problem.Things are exactly and correctly the
way they should be.Then you end the SP session and start a DM
one.Now,even tho' the setDM.cfg specifies a higher brightness value,say
3, and the game starts fine,the value 3 is not effected game-wide.
Weapons and monsters are brighter than your previous SP
session but textures remain the same,darker than it should be if
brightness was really 3.The relevant registry setting,however,gets
updated to brightness 3(since it's specified as such in setDM.cfg).At
this point,quit and restart a DM session and everything within the
game will be brighter,i.e. brightness 3 is effected game-wide.Now
understand if you had started an SP session in this instance instead of
DM,brightness  for weapons/models will be at 1(since you specified so
in setSP.cfg which gets executed everytime you start the game with the
SP s/cut) but textures remain at 3(since in the session prior to
restart, setDM.cfg specifies brightness 3).So,when you switch between SP
and DM gaming sessions randomly,things are never the way you think
they are if you trusted your config setting.

I hope all that came out intelligibly.

The main point is that brightness,gamma,texgamma and lightgamma work on
the fly only for entities and not the world. For the world to be effected if
changes are made whether in-game or in a specially executed cfg between SP
and DM sessions,it must be restarted.

I've scratched and scratched my head about this and have lost much hair :-(
I can't think of any way to overcome this damning part about an otherwise
superb game.No alias seem to work,whatever permutations I try.

For anyone who always switches and mixes up modes of gameplay, i.e. SP and
DM, randomly, the only way around this that I can come up with without
the annoying start/quit/restart routine for every gaming session be it SP or DM is
to create two separate .reg files, one for each mode of gameplay, and execute
the relevant .reg file b4 each SP or DM session, just to be doubly sure that the registry
shows the correct brightness setting prior to a session (yes, I go with the .reg file way
as it's less cumbersome than running regedit and drilling down to the appropriate path).
The .reg file's content only consist of the brightness setting. Gamma for both SP and
DM is left at 3 permanently. Texgamma and lightgamma is never read from the registry,
even if you specify a string value manually it is never read, so that means leaving the
two a constant as well.So,in my case,brightness 1 in something called,say, H-L-SP.reg
and brightness 3 in H-L-DM.reg (the glare will be visible in DM however becoz of
texgamma and lightgamma remaining constant at 3 and 2 respectively...wtf,in DM,
fragging is the primary objective anyway).

So,the H-L-SP.reg file for SP(to be executed b4 any SP session) would
contain this:

(1)   REGEDIT4

       [HKEY_CURRENT_USER\Software\Valve\Half-Life\Player Profiles\Player\CVAR]
       "brightness"="1.000000" <enter>

and for H-L-DM.reg :

(2)   REGEDIT4

       [HKEY_CURRENT_USER\Software\Valve\Half-Life\Player Profiles\Player\CVAR]
       "brightness"="3.000000" <enter>

After all that,I hope you understand what I'm trying to get you to understand.
______________________________________________________________________

And I hope everyone who reads this guide gets what I'm trying, in a less than scholarly fashion, to say. If you do understand what I'm trying to get across and want to create the mentioned .reg (registry script) files but don't know how,it's easy :

Right-click anywhere in C:\Half-Life\ and select New Text Document. Copy and paste ,starting with (1), the above blue text onto it (make sure you press <enter> after the "brightness"="x.xxxxxx"), save it as say,H-L-SP.reg.You'll be prompted whether you're sure,click yes. Repeat for (2) and name it as ,say, H-L-DM.reg
You can then just create a shortcut to these two .reg files on the desktop. Double-click them, click yes when prompted, OK when prompted again then start your game.Remember,execute the correct .reg file for SP or DM.
Now, if you follow this .reg way, then you might as well permanently leave out the Brightness setting in your configs.
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