Line of sight

All units, both X-Com and alien, have a line of sight. A unit's line of sight encompasses any objects or other units which are:

• Within visible range

Visible range for X-Com soldiers is 20 tiles during the day and dawn/dusk, 9 at night

Aliens are not subject to the lighting penalties and have a 20-tile range at all times

• Not blocked by terrain, smoke, or other units
• Within the unit's field of vision

All units have a 90 degree field of vision, radiating outward in a cone in whichever direction they are facing.

Unit facing South. Visible squares are in white.

Unit facing Southeast. Visible squares are in white.

• Note that line of fire is not necessarily the same as line of sight. There are cases where you can shoot around objects (such as corners) that you cannot see around, and you can always shoot beyond the 21-square visual range (see Sniper Tactics). You can also shoot through smoke that you can't necessarily see through.

• Notice that your cone of vision means that you can't see aliens right next to you when you go through a door. But you only have to turn in place once to see a given side in that situation, not twice. Thus, a total of 3 turns-in-place (once to the left, then two to the right) will show you if anyone's on either side of you. Turning in place does not trigger reaction fire.

• There are cases where aliens can see around corners (and shoot at you) when you cannot see them. This phenomenon is not fully understood at this time.

[Need diagrams of LOS around corners/beyond roofs.]

• In certain cases, it is possible to see into a UFO from the outside (see External UFO Windows).