itch.io

Uses two-dimensional "sprites", 2D images created and used on a flat plane, as opposed to the three-dimensional models or environments found in 3D games.

Resources relating to or for building Graphical User Interfaces (Commonly called GUIs)

Games where you have to manage resources in order to complete objectives. 

PNG, or Portable Network Graphics is a common image file format that is lossless, can contain an transparency channel, and compressed. An ideal format for distributing static assets without any loss in quality.

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

Unreal Engine is a 3D game creation tool

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