Red Blob Games

What it is

Red Blob Games is Amit Patel's site of interactive tutorials on game-related algorithms and maths. He has been helping people make games since 1990, according to the site, and every article is free with no signup and no ads. The accompanying code is open source under permissive licences.

Well-known articles include:

• Introduction to A*: breadth-first search, Dijkstra's algorithm and A*, with diagrams you can change.
• Hexagonal Grids: the standard reference for hex coordinates, distances, lines and rotation.
• Making maps with noise: procedural terrain from noise functions.
• 2D visibility: line of sight and lighting in 2D.
• Pages on grids, graphs, Voronoi diagrams and Delaunay triangulation.

Is it worth it?

Yes, when your game needs one of these topics. The interactive diagrams are the fastest way to understand pathfinding or hex grids properly rather than copying code you do not understand. The A* and hex grid pages are recommended in game development communities year after year.

When to use it in the roadmap

In the maths and feel stage, and whenever you build enemies that need to find a path, a strategy game on a hex map, or procedural levels. Engines include navigation systems for 3D, but knowing how pathfinding works helps you debug them and write your own for grid-based games.

Time and prerequisites

Each article is an hour or two of reading and experimenting. Basic programming and school-level maths are enough.

Free vs paid

Free.

Common questions

Are there code samples? Yes, most articles include implementation notes, and code in several languages is linked.

Is it only for 2D? Mostly 2D and grid based, which is where the ideas are clearest; the same algorithms apply in 3D.

A good way to study an article

Read the article once while playing with every diagram. Then close it and write the algorithm in your own engine for a tiny test scene, such as a grid of walls and a character that walks to where you click. Come back to the article only when you are stuck. This turns an enjoyable read into a skill you can use in a jam or explain in a studio technical round.