step - 16

Game.kt

fun play(first: Throw, second: Throw): Winner {
    if (first == second) {
        return TIE
    }

    return when (first vs second) {
        // classic rules
        SCISSORS beats PAPER,
        PAPER beats ROCK,
        ROCK beats SCISSORS -> FIRST_PLAYER

        // additional modern rules
        ROCK beats LIZARD,
        LIZARD beats SPOCK,
        SPOCK beats SCISSORS,
        SCISSORS beats LIZARD,
        LIZARD beats PAPER,
        PAPER beats SPOCK,
        SPOCK beats ROCK -> FIRST_PLAYER

        else -> SECOND_PLAYER
    }
}

private infix fun Throw.vs(other: Throw) = this to other
private infix fun Throw.beats(other: Throw) = this to other