Originally added for the Opposing Force add-on, and now available for all mods with the 1.0.1.6 update, the strings.lst file allows for nearly every string in the Half-Life launcher to be customized. To make use of this function, you'll need to reference the files resource.h and hl_res.rc. 

To customize a string using strings.lst, first enter the number of variable you wish to modify (as listed in resource.h), then the new value in double quotes. So, in the included example, the line:

195 "Order the full version of Half-Life: Opposing Force."

alters the value of IDS_MAIN_ORDERHELP. Thus, the format for strings.lst is:

[index] "string"


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INCLUDED FILES
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- HL_Res.RC	used to determine which string variables display what text
- resource.h	used to look up the index of the string (for use in strings.lst)
- strings.lst	the actual file you will include in your mod