itch.io

16 pixels by 16 pixels is a common resolution for assets matching a low-res pixel art aesthetic. Although the assets may not be specifically 16x16, they are designed to work in a graphical setting where objects are around that size.

Graphics for creating characters

Unity is a game engine for 2D, 3D, AR and more

Resources for building and relating to User Interfaces, how the user interacts with your program