RetroBlit is a different kind of retro pixel game framework (really). It aims to create an ideal, low friction framework for making pixel-perfect retro games from the early 90s era. RetroBlit takes advantage of the portability, and the ease of deployment that Unity provides, but does away with the Unity Editor interface in favour of a traditional game loop, immediate-mode, and code-only development.
Check out the RetroBlit feature demoreel at itch.io!
Try the WebGL example demo games BrickBust and Retro Dungeoneer which ship with RetroBlit (all source code and assets included).
For a more information and a very in-depth documentation please have a look at these pages: