[HelloNurse]

This is naive pathfinding that adopts the shortcut of perfect information. Good looking pathfinding simulates realistic terrain ignorance (no "psychic powers"), but it is likely to be expensive enough to require other compromises (e.g. updating paths less often).

[card_zero]

You reckon the perfect information version is cheaper than an algorithm that works only on the tiles near to the unit? But this quickly gets too complicated to discuss; there's the confusing matter of precalculation versus live updating.

[sdwr]

The perfect information version calculates the path once on click, the local version needs to recalculate every time the unit moves (and new tiles are "seen")

[daymanstep]

Recalculating the path every game tick is too expensive. What brood war did was to just have units wait for a second when they collide with something before recalculating the path. This resulted in horrendous "traffic jams".

It's also why Brood War players got into the habit of spam-clicking, because the game would recompute paths every time you issued a command, so spam-clicking resulted in smoother movement.