The mapster3.exe file you have requested: Utilities / Mapping / Mapster 3 - 1.08mb 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:
Mapster allows for multiple computers, to compile a map at the same time. Majorly cutting down on the time it takes to compile. The set up process is very simple and it's definately for a usefull cause.