Nope, You will notice that after spawning essence of darkness in each city.
And, if You are in game while world failed, You will see following messages:
One of the flames has gone out. All hope is lost!
One of the ten lights went dark and disappeared! All hope is lost now. Flee into your houses and hope to survive this day.
Strong demonic creatures have passed the border to our world and invade the Temple of Light! Run, as long as you still can - or fight them, if you dare!
You can also check temple of light (bad side) and check if monsters have spawned there. if world fails, there will be some special monsters.