Anti-aliasing (or "AA" for short) is an advanced pixel art technique that is used by pixel artists everywhere.  Although it is a widely used technique, there are certain "rules" when it comes to using it in Cytopia.  This tutorial will help explain when you should use this technique, and when you shouldn't.  This is NOT an AA tutorial though.  If you'd like to learn more about that there are plenty of sources online that can teach you about it.

When NOT to use AA:
As a general rule while making sprites and textures for Cytopia, you should avoid using AA by default.  The reason being that most of the time it doesn't look good with the style of the game.

Most of the buildings in Cytopia have hard, well-defined lines that make it easy to see where the side of a building starts and ends.  AA is not good for this because it blurs those lines and goes against Cytopia's style.

When to use AA:
Like I said before, you should avoid using AA while making graphics for Cytopia.  However, there are a few specific situations where AA might come in handy.

The most notable example would be icons.  If you are making icons for a category or some other part of the UI, AA would be a great technique to use there.  It'll help make circles look more round, and improve their shading.

Another situation AA can be applied in is if you are trying to make a sign for a building.  With the limited resolution you have to work with, it can be difficult to make something as small as a sign while retaining all of its details.  AA can help with that, as it allows for more detail to be placed in a small area.

For example:
In this situation, I was trying to make a sign with a soccer ball on it.  Although the difference may look small, it really helps make the soccer ball look more round, especially at a distance.