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32 pixels by 32 pixels is a common resolution for assets matching a low-res pixel art aesthetic. Although the assets may not be specifically 32x32, they are designed to work in a graphical setting where objects are around that size.

Science-fiction. Commonly including things like aliens, advanced technology, and settings of outer space or distant planets. 

Sprites are generally 2D images used in games to represent objects. They can be animated or static, and come in different styles like isometric or top-down.