This is a great one from Nik Morris who shows how to create pixel art animation in After Effects.

Actually Nik shows how to bring in Pixel Art Animations from the free aSprite Animated Sprite Editor into an HD After Effects projects, and have it still looking great.

This tutorial explores the common failure points when bringing your pixel artwork into a 1080p comp in After Effects

Aseprite is an Animated Sprite Editor and Pixel Art Tool designed to look and operate like the sprite editors of old and is a free download for Windows and Mac Platforms.

Nik covers topics such as scaling and looping the animations, and also provides workflow tips for preparing your frames for animation in the free sprite editor Aseprite as well as Photoshop.

Check out the tutorial for How to Animate Retro Pixel Art in After Effects here.