Complex sentence: Each contestant wins ¥10,000 for every box they held at the end of the game; if one contestant holds all twenty-five boxes at the end of the game, then their winnings are increased to ¥500,000.
Split into simpler sentences: Each contestant wins the amount of yen for every box they held at the end of the game. But, if one contestant holds all twenty-five boxes at the end of the game, then their winnings are increased to ¥500,000.