SourceMod
From HLSW Wiki
Info:
SourceMod is a scripting API to the SourceMM (Metamod: Source) plugin API to Source engine games.
This plugin is provided by the same team that brough you AMXModX in Half-Life 1 (GoldSRC) engine games.
It allows a versatile, powerful, and fast way to achieve scripting, with minimal CPU usage and performance load on the server.
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