Push the green START domino to begin the chain reaction. Show the complete domino falling process. The dominos fall step by step from left to right. The dark gray trunk falls first, then splits into the bright red Branch A (upward) and indigo Branch B (downward). Branch A has a gap marked with a red X that stops the chain reaction in that branch. The final state shows Branch A with fallen dominos before the gap and standing dominos after, while Branch B completes fully. Only modify what the task requires; keep the background and any other element unchanged.