INFLUENCE RADIUS
Effects projected in a circle around a source — a tower's coverage area, a city's workable tiles, an aura's buff range, a building's happiness effect on nearby homes.
- SOLO-DEV COST LOW
- TIMING REAL-TIME / TURN
- COMMON IN 4X · CITY-BUILDER · TOWER-DEFENSE · STRATEGY
Civilization's city borders and workable radii structured 4X land value for decades, city builders like Anno and Caesar price every service building by its coverage circle, tower defense is influence radii weaponized, and colony sims radiate temperature, beauty, and noise from sources. Designers use radii because they convert placement into optimization: when every building projects a circle, positioning becomes a packing problem — overlap wastefully or leave gaps riskily — and the map's geometry (chokepoints, terrain, existing structures) suddenly prices every tile differently. Radii are also supremely legible: a drawn circle communicates an entire rules interaction instantly. Key decisions: hard circles versus decay-with-distance gradients (hard edges are legible but create absurd one-tile cliffs; gradients are realistic but murky), whether radii can be extended or overlapped for stacking benefits, and when to show the circles — always-on overlays clutter, placement-time-only hides ongoing coverage gaps. Pitfall: too many invisible overlapping radii — when a dozen unseen circles govern a tile's performance, the optimization game the mechanic promises becomes unplayable spreadsheet archaeology, and players place buildings by vibes while the system silently punishes them.