Here's a little 8x8 pixel animated flame I managed to make. It plays nicely in 20 FPS (0.05 second delay between each frame) :)

Notice how the different resolutions are just scaled versions of the smallest one. This is because some game engines and all that scale images so that they become blurry. That's why I made the scaled versions. E.g. in the example image I used LÖVE or Love2d, which you can find here. I was lazy and didn't want to search how to make it not blurry, so I just scaled the tiles to make them more accurate.

Looks nice on some wood or stuff.

Remember, this is not a GIF, so it doesn't play automatically. You have to program that yourself.