Mobile Tower Defense Game Development
Tower Defense presents interesting balance between strategy depth and accessibility. Technically, complexity determined by two things: performance with large enemy count and pathfinding system correctness.
Pathfinding: why A* isn't enough here
Standard A* recalculates path for each agent individually. With 100+ enemies on scene, that's 100+ navigation mesh requests per frame. On mid-range Android, 4–8ms for pathfinding alone.
Solution: Flow Field Pathfinding. Compute one direction field for entire map once (when route changes due to new tower), each agent simply reads its direction from field texel at its position. Recalc only on tower placement/removal, not every frame. With 200 agents on iPhone 12—0.3ms instead of 6ms.
In Unity implemented via NativeArray<float2> (directions) + Job System for parallel agent position updates. Unity DOTS Entities perfect for TD agents.
Towers: data-driven design
TowerDefinition ScriptableObject contains: attackRange, attackSpeed, damage, targetingStrategy (First, Last, Strongest, Closest), damage type. TargetingStrategy is Strategy pattern: ITargetingStrategy with FindTarget(List<Enemy> inRange) method. Adding new targeting mode is one new class, zero changes to existing code.
Tower upgrades stored as TowerUpgrade[] array in same SO: each level contains delta to parameters. Designer sees full upgrade table right in inspector.
Visual feedback and UX
Critical for TD: tower attack range must display on hover or placement. Implementation: decal or LineRenderer in circle shape. On tower placement, check via Physics2D.OverlapCircleAll that enemy path isn't completely blocked (game shouldn't allow tower placement that makes level impossible).
Timeline: TD with 10 tower types, 15 levels, basic progression—3–5 months.