Apart from the code, wich you can look though of course, here the mechanics of that guy:
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This AI is based on finding a movement path without
the need for creating a node-based pathfinding grid.
The nodes are created "on the fly" by the player when he moves.
The player continiusly "drops" nodes when walking.
As the nodes are in a linked list, they somehow form a
"chain", wich is the path for the AI to move.
The AI guy looks for the most recent node, that he can directly reach.
Once he is there, he will go to an even more recent node.
Similar to a Dog, sniffing his way.
This way the AI follows the player.
I dont remember exactly, but I think, when the AI gets stuck,
he walks back his way, until he can find a suitable node again
to follow.
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The other part is the movement script, wich uses
several traces, that makes the AI avoid to get to close to walls.
So before colliding directly with something, the AI usually pushed itself away from the obstacle or turned a bit.
The same with jumping. The Players actually hover over the ground up to the hips.
Similar to humans, the legs are basically
fully flexible to adapt to narrow obstacles on the floor.
If the trace dow finds a distance lower than the leg-hight, the
AI pushes itself up. If it is higher than the hip-hight, it
stops pushing, and starts to fall.
