Here is the full list of all 19 UnnyWorld - there are Battle Royale achievements.
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Slain 1000 heroes
Achieve Gold League in Arenas
Win in Planet Invasion 25 times
Achieve Silver League in Arenas
Buy a chest
Unlock 7 heroes
Protect your Planet from Evee.
Slain 10000 heroes
Slain 100000 heroes
Achieve Platinum League in Arenas
Achieve Champion League in Arenas
Win in Planet Invasion 500 times
Win in Planet Invasion 2500 times
Upgrade Ondu to level 6
Win in Bang-bang Party arena 2500 times
Win in Rocket depot arena 2500 times
Change the name for gems
Win in Battle Royale 10 times