Base frame. Generate the subject in its neutral/starting pose with full style words, flat keyable background, side/game-appropriate view (game-asset-core defaults apply).
Animate. image_to_video from the base: one clear motion, in place, static camera ("the knight walks in place, side view, camera locked", 6s). Keep the shot simple — one subject, one motion.
Harvest. Extract densely: ffmpeg -i clip.mp4 -vf fps=12 f%03d.png (~72 frames from 6s). View them as a set (contact sheet or batches).
Select. Pick the frames that (a) capture the motion's distinct phases and (b) LOOP — the sequence's end must flow back into its start. Don't force a count: if the motion reads best with 8, 10, or 12 frames, deliver that many (more frames = smoother in-engine; they're already generated). For a cycle, select one full period, using motion landmarks (foot contacts, wing extremes, flame peaks) to find period boundaries.
Clean. Video frames may drift from the base's palette/crispness or background. If needed, run selected frames through image_edit to restore the flat background/style ("same pose exactly, restore the flat #hex background and cel-shaded style"), or key/clean with PIL. Verify cleaned frames didn't change pose.
Package. Deliver frames in play order (zero-padded names) and/or composite a sheet per game-asset-core sheet rules (uniform cells, no dividers). State the intended fps.

Fall back to keyframe-by-keyframe image_edit generation only when video fails the motion (rare: very stylized poses, single dramatic keyframes) — and then plan phases yourself and obey the laws below.

Motion laws (verify against these, whatever the pipeline)

Cycles loop; alternating gaits spend half the period mirrored.
Continuity: limbs, props, anatomy, effects move on continuous paths — nothing teleports, vanishes, or duplicates between adjacent frames.
Physics reads in stills: airborne shows air, anticipation compresses, follow-through overshoots; effects stay anchored to their origin unless the request moves them.
Energy matches the ask: idle/subtle means barely-different frames.

Verify — the flip test

View the final frames strictly in order and narrate the motion; check loop closure explicitly (last→first). A hedge in your narration is a failed frame. The video pipeline usually passes this on the first try — that's why it's the default.

game-animation-frames

Animation Frames — video-first

Default pipeline