An outline, and the pieces that make it. Every piece belongs somewhere, turned some particular way, and there is one arrangement that fills the shape with nothing spare and nothing overlapping. Drag to place, tap to turn. A piece dropped a square off snaps to the nearest fit rather than being refused, because a near miss is what you meant. Anything placed can be pulled straight back out, so nothing is ever lost and no board can be spoiled. One piece on every board already sits the right way up, so there is always somewhere to start. The move target is measured rather than assumed: a square looks the same after turning and a domino looks the same after half a turn, so the game does not charge for rotations nobody needs to make. There is no timer and no way to lose. The board waits.
Turn and place every piece so the outline fills exactly. No gaps.