Line of sight
Determines what a unit can see and target: walls block vision, elevation extends it, smoke and foliage degrade it. LOS is the information layer of tactical play — it defines where you can shoot, where you can hide, and what the enemy knows, making geometry itself a weapon. Designers use it to create ambush and scouting play (paired with fog of war), to give maps tactical texture (sightline design is level design), and to make positioning rich: the same tile is safe or lethal depending on angles. Implementation is famously fiddly: tile-based raycasts produce corner cases — literally, peeking around corners — that players perceive as bugs whenever the visualization disagrees with the rules; XCOM-likes carry long histories of LOS-indicator refinement. Key decisions: symmetric versus asymmetric sight (can I see him if he sees me?), partial visibility states, height interaction, and above all UI: preview exactly what a move will reveal and expose before the player commits. Pitfall: rules that differ from what the camera shows.
- Dev effort: Medium
- Timing: Real-time or turn-based
- Common in: tactics, strategy