The idea
@keyframes names a set of frames, and animation-name attaches them to an element. Inside the block, from/to (or 0%/100%) set the styles at the start and end.
The stage freezes every animation at its end — animation-play-state: paused plus a negative animation-delay plus animation-fill-mode: forwards — so you can see where the box lands. Write the keyframes that slide it 200px to the right.
This level needs animation-name — that is the whole point of it.