GAME OVER!

Change the rules and players can’t come back. Drop them into the abyss and before they know it, you changed their game mode too.

Try the code:

player.onChat("gameover", function () {
    gameplay.setGameMode(
        SURVIVAL,
        mobs.target(ALL_PLAYERS)
    )
    mobs.teleportToPosition(mobs.target(ALL_PLAYERS), pos(0, -1000, 0))
    loops.pause(1000)
    gameplay.setGameMode(
        CREATIVE,
        mobs.target(ALL_PLAYERS)
    )
})