The RESGen.exe file you have requested: Tools and Utilities / Mapping / RESGen - 116kb is not available. Perhaps try browsing all files for the game Half-Life and upload any files you want to share or are missing. This is the only information we could locate:
Great tool for anyone who uses Valve Hammer Editor to make maps for Half-life or a variety of other games and mods.
This program makes you a res file for any map you want one for.
A .res file is needed if you are hosting Great tool for Valve Hammer Editor mappers.