Line of sight
LOS is one of important Statistics of living entities, that affects how far they will detect opponents and items within their Line of sight.
Line of sight is used for detecting enemies to engage, and for ranged attackers determines their attack range (If i can see you, i can shoot you). It's also used by heroes and civilians to detect happiness boosting decorations.
Line of sight currently works only on creature's level, they can't detect objects on other levels even if they are close, also it requires straight unobstructed path to target object, walls and pits break LOS, rendering creation archer battlements impossible.