|Orcs tend to start with low perception..and thus can't see very far.
When deciding what features to add to graphical mode, one of our core rules is: graphical shouldn't show stuff that you don't know about in ASCII mode*. Just allow you to see more at a glance. So one promintent feature we haven't touched yet that fits this rule really well is Line of Sight.
How far you can see is dependent on your perception and modified by a wide range of factors. And yet ADOM does provide the current exact view range directly - the "l"ook command clearly states where your LoS ends by adding a "you recall:" prefix for tiles that are not currently visible.
However, the game doesn't give any clear visual indication, so we're experimenting with that right now. Zeno is doing his magic again so that you don't have any doubts where your sight range ends :)