Red Blob Games

What Red Blob Games actually is

Pathfinding, hexagonal grids, map generation, curved paths and line-of-sight all get reference-quality treatment here, written by Amit Patel for people building games. Almost every page carries interactive diagrams where you move the start and goal and watch the algorithm rerun.

Why it is worth your time

The A-star page became the standard explanation of pathfinding largely because you can drag an obstacle and see precisely which nodes the search stops visiting.

Common questions

Is Red Blob Games free?

Yes. Red Blob Games is free and does not ask you to register or hand over an email address before you can use it.

How long does Red Blob Games take?

Clear your evening. We warned you. We file it under "Rabbit hole" — game maths, explained with diagrams you can drag.

Does Red Blob Games work on a phone?

Red Blob Games really wants a mouse and a wide window. It will load on a phone, but the experience is built for desktop.

What kind of site is Red Blob Games?

We list it under Explain Everything — hard things, made suddenly obvious. The A-star page became the standard explanation of pathfinding largely because you can drag an obstacle and see precisely which nodes the search stops visiting.