Metamod plugs into the game engine directly.
Sourcemod plugs into metamod and routes all it's calls through MM (at least, I think that's how it works).
The idea is that other plugin developers can code their plugins to hook into metamod and thus run alongside sourcemod without conflicts.
The concept was carried over from the original metamod plugin (
www.metamod.org). There was (and still is) no official method of plugging into HLDS - what metamod does is pretend to be the game .dll file.
The first thing metamod does on load is load the game dll as a "plugin" - this means metamod sits directly between the HLDS engine and the mod, enabling it to do all kinds of fun things.
http://video.google.com/videoplay?do...51453430573504
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