A* Algorithm vs Unity NavMesh: Choosing the Right Pathfinding for Your Game

Source: Dev.to

What’s A*?

A* (A-star) is a search algorithm used to find the shortest path between two points on a grid or graph.

What’s Unity NavMesh?

NavMesh is Unity’s built‑in navigation system.

When to Use A* Algorithm

• ✅ 2D Grid‑Based Games – great for top‑down, tile‑map games like Pokémon, Fire Emblem.
• ✅ Custom Pathfinding – you need full control over the algorithm or grid.
• ✅ No Unity Engine (Custom Engine) – you’re building from scratch.
• ✅ Dynamic or Procedural Worlds – you generate maps at runtime and need custom solutions.
• ✅ Low‑poly / Small Worlds – simple grid = fast A* computation.

When NOT to Use A* (Use NavMesh Instead)

• 🚫 3D Terrain or Complex Geometry – A* doesn’t understand 3D mesh surfaces.
• 🚫 Need Agent Features – no built‑in agent radius/height, obstacle avoidance.
• 🚫 Performance Bottlenecks in Large Maps – grid‑based A* gets slow as grid size increases.
• 🚫 Want Auto Pathfinding in Unity – Unity NavMesh does the heavy lifting automatically.

When to Use Unity NavMesh

• ✅ 3D Games (FPS, Adventure) – works out of the box with terrain, stairs, ramps.
• ✅ You’re Using Unity – built‑in, highly optimized, works with Agents and Obstacles.
• ✅ Want Dynamic Pathfinding – NavMesh can update with NavMesh Surface or Carving.
• ✅ Need Agent‑Based AI – handles multiple AI units with different sizes/behaviour.

When NOT to Use NavMesh (Use A* Instead)

• 🚫 2D Games – NavMesh is mainly for 3D navigation (2D support is hacky).
• 🚫 Fully Dynamic Worlds – you can’t rebake NavMesh instantly at runtime.
• 🚫 Custom Game Engines – NavMesh is Unity‑specific.
• 🚫 Hex or Irregular Grids – NavMesh doesn’t support custom‑shaped tile systems natively.

NavMesh Demo Project

Find my NavMesh Demo Project here

TL;DR Summary

• Top‑down 2D tile game → A*
• 3D Adventure/FPS → NavMesh
• Procedural dungeons → A*
• RTS / MOBA (3D with units) → NavMesh
• Custom logic / AI testing → A*
• Unity 3D project with terrain → NavMesh

Handling Dynamic Environments in a 3D Game

How do I handle dynamic environments in a 3D game where the NavMesh must update instantly at runtime?

Unity’s built‑in NavMesh system is not ideal for highly dynamic environments, but there are workarounds and better solutions depending on your game’s needs.

Why NavMesh is Limited in Dynamic Worlds

• NavMesh baking is not real‑time; it takes time and can’t be rebaked every frame.
• NavMeshObstacle with carving only supports simple object avoidance.
• Large‑scale changes (terrain deformation, new platforms) are not handled efficiently.

Typical dynamic scenarios that expose these limits:

• Moving platforms
• Changing terrain
• Buildings spawning/despawning

Best Solutions for Real‑Time Navigation in Dynamic 3D Worlds

• ✅ NavMesh with Carving – suitable for minor changes like doors, crates, small obstacles.
• ✅ NavMeshComponents package – use when only parts of the environment change.
  • NavMeshComponents on GitHub
• ✅ A Pathfinding Project (by Aron Granberg)* – best for fully dynamic 3D worlds.
  • Supports grid, navmesh, and point‑graph types.
  • Real‑time updates & graph recalculations.
  • Optimised and widely used in indie and AAA titles.
  • Free version
  • Paid version on Unity Asset Store