Blood moon
Added in v1.0.1
Minecraft's Hard mode stops being scary after a while. Once you have a base, armor and food, every night feels the same. I wanted to spice it up with a real deadline to prepare for: the blood moon.
It only exists on Hard difficulty and comes back every 100 days.
The countdown
Every morning, the game shows how many days are left. No point cheating by moving the clock forward: skipped days count too.
Day 100
From the morning, the sky turns red and the grass slowly turns into dirt. In the evening, the moon rises, huge and red, and the screen takes on a nightmare look.

All night long, hordes of monsters arrive in waves around every player, more and more of them and often well equipped. Between two waves, you get a few seconds to catch your breath.
Tip. Prepare a shelter, torches and food before day 100. If you're playing with others, stay together.
Dawn
If you make it to morning, you win. A cutscene celebrates your survival, then a report names the best and worst of the night: who killed the most monsters, who died the most.
Testing it
An operator can jump straight to day 100:
/time set bloodmoon