Used by the routine at OBEY.

Calls CHECK_WON and CHARACTERS_ACT -- has the player won, and every other character's turn -- and then walks TIMERS. A timer whose count is zero is not running. One that is running counts down by one a turn; on reaching zero it runs its routine, and in the turns before that, while the count is no more than its warning span, it runs its warning routine instead.

Only one timer fires in a turn. A second one to reach zero in the same turn is held at a count of 1 and fires in the next, so two events never land on the player at once -- though a held timer with a warning span runs its warning this turn instead, and BARREL_REACHES_LAKE clears TIMER_FIRED as it starts, so it does not use the turn's firing up.