I've played an unhealthy amount of HL2 and spent a while modding it, and I don't believe this is true. People say things like this a lot about games with decent AI. For example, the old quake 3 hoax about bots "learning" to become peaceful on a server that was left running for 4 years. It's fun to imagine the AI as more than just a set of scripts.
The Valve Developer Community has some okay documents about the AI [0], moddb has some nice articles too (no links offhand). And most of the source for combine guards is available in the Source SDK [1], you can see tons of if's and hard coded sequences of actions.
I've read that the AI was changed after the Orange Box release, so maybe there was some learning features to them originally. Or maybe those features do exist within HL2's private source files, though it doesn't "feel" like it.
The Valve Developer Community has some okay documents about the AI [0], moddb has some nice articles too (no links offhand). And most of the source for combine guards is available in the Source SDK [1], you can see tons of if's and hard coded sequences of actions.
I've read that the AI was changed after the Orange Box release, so maybe there was some learning features to them originally. Or maybe those features do exist within HL2's private source files, though it doesn't "feel" like it.
[0] https://developer.valvesoftware.com/wiki/AI_Learning:_Combin...
[1] https://github.com/ValveSoftware/source-sdk-2013/blob/master...