Update: adding in the front-quarter walk-cycle animation. There are 5 different spritesheets: front, rear, side, front-quarter, and back-quarter.
The quarter and side ones are flipped in X to give a full 8-way facing character.
I find the front walk cycle particularly hard because instead of just being able to use just limb rotations, you need to do a lot of image switching and scaling. Scaling is used to make the rear-ward leg in the walk have that limb and foot appear to go back and up.
Notice also the feet: as the leg extends towards you the bottom of the foot becomes visible. This does not come for free. It is done by swapping the foot image from a top down one, to one where the foot is viewed from below. Its a different sprite altogether and I tell Spine to switch one sprite for the other at just the right moment so that it looks completely natural for the walk.
The image switching is also used for the eye-blink that happens as Erin's right foot hits the ground.
I am pretty impressed by Spine so far - it really is a pro bit of software. Just wish it had been around a year ago. :-)
This video published recently on my YouTube channel explains some of the thinking behind the move to Spine, and also compares the previous tech stack's deliverables with that of Spine.
I didn't show it in that video but here below is the Spine sprite sheet: