So I was told about the Lizard and Spock extension to Rock, Paper Scissors and I wanted to see how the current OOP approach would extend to the introduction of the new winning methods and roles.

gistfile1.php

<?php

class DrawException extends DomainException {}

abstract class Hand {

    public function beats(Hand $hand) {

        $this->rejectDraw($hand);
        return $this->assess($hand);
    }

    protected abstract function assess(Hand $hand);

    public function __toString() {

        return get_class($this);
    }

    public function rejectDraw(Hand $hand) {

        if ($hand === $this) {
            throw new DrawException('No player wins, round is a draw');
        }
    }
}

interface Wrappable {}
interface Cuttable {}
interface Bluntable {}
interface Beheadable {}
interface Vapourisable {}
interface Crushable {}
interface Poisonable {}
interface Edible {}
interface Disprovable {}
interface Smashable {}

class Rock extends Hand implements Wrappable {

    protected function assess(Hand $hand) {

        $retval = ['result' => false, 'method' => null];

        switch (true) {

            case $hand instanceof Bluntable:
                $retval['result'] = true;
                $retval['method'] = 'Blunted';
                break;

            case $hand instanceof Crushable:
                $retval['result'] = true;
                $retval['method'] = 'Crushed';
                break;
        }

        return $retval;
    }
}

class Paper extends Hand implements Cuttable, Edible {

    protected function assess(Hand $hand) {

        $retval = ['result' => false, 'method' => null];

        switch (true) {

            case $hand instanceof Wrappable:
                $retval['result'] = true;
                $retval['method'] = 'Wrapped';
                break;

            case $hand instanceof Disprovable:
                $retval['result'] = true;
                $retval['method'] = 'Disproven';
                break;
        }

        return $retval;
    }
}

class Scissors extends Hand implements Bluntable, Crushable {

    protected function assess(Hand $hand) {

        $retval = ['result' => false, 'method' => null];

        switch (true) {

            case $hand instanceof Cuttable:
                $retval['result'] = true;
                $retval['method'] = 'Cut to death';
                break;

            case $hand instanceof Beheadable:
                $retval['result'] = true;
                $retval['method'] = 'Beheaded';
                break;
        }

        return $retval;
    }
}

class Lizard extends Hand implements Beheadable, Crushable {

    public function assess(Hand $hand) {

        $retval = ['result' => false, 'method' => null];

        switch (true) {

            case $hand instanceof Poisonable:
                $retval['result'] = true;
                $retval['method'] = 'Poisoned';
                break;

            case $hand instanceof Edible:
                $retval['result'] = true;
                $retval['method'] = 'Eaten';
                break;
        }

        return $retval;
    }
}

class Spock extends Hand implements Disprovable, Poisonable {

    public function assess(Hand $hand) {

        $retval = ['result' => false, 'method' => null];

        switch (true) {

            case $hand instanceof Smashable:
                $retval['result'] = true;
                $retval['method'] = 'Smashed';
                break;

            case $hand instanceof Vapourisable:
                $retval['result'] = true;
                $retval['method'] = 'Vapourised';
                break;
        }

        return $retval;
    }
}


$hands = [
    'r' => new Rock,
    'p' => new Paper,
    'sc' => new Scissors,
    'l' => new Lizard,
    'sp' => new Spock
];

while (true) {

    echo "\n\nChoose hand [r (rock), p (paper), sc (scissors), l (lizard), sp (spock)]: ";

    $choices = [
        'computer' => array_keys($hands)[rand(0, count($hands) - 1)],
        'player' => strtolower(trim(fgets(STDIN)))
    ];

    $computerHand = $hands[$choices['computer']];
    $playerHand = $hands[$choices['player']];

    echo "Player chose $playerHand\n";
    echo "Computer chose $computerHand\n";

    try {
        $result = $playerHand->beats($computerHand);
        if ($result['result']) {
            echo sprintf("Player wins, %s beats %s by being %s\n", $playerHand, $computerHand, $result['method']);
        } else {
            echo sprintf("Computer wins, %s beats %s but I don't know by which method\n", $computerHand, $playerHand);
        }
    } catch (DrawException $ex) {
        echo $ex->getMessage() . "\n";
    }
}