From Game Making Tools Wiki
GIFs have become a pretty standard way to promote games. Lots of game pages on Itch use them as their main image, for example.
- Making Chained GIF Cover Images in Linux [Easy Mode] - Guide by Alex Griffith on making GIFs using Peek and the CLI tool Gifsicle.
All free, unless specified.
- Peek - Github
Record your screen straight to a GIF (or video)
- Glimpse and Gnu IMP
Can create GIFs from several images. In brief: put each frame of the animation on its own layer, and export as a GIF.
- FFmpeg - Homepage
General tool for working with audio and video. Can extract frames from a video as images, piece together images into a video or GIF, and convert video to GIF.
- Gifsicle - Homepage
GIF-dedicated tool for creating, editing, and even comparing GIFs.
- ImageMagick - Homepage
General tool for manipulating images. Handy for creating animations out of sprite sheets. It can do everything.
- Yeetgif - Github
Add animated effects. Has channer vibes though.