Here is the full list of all 32 Millennium 2 - there are Take Me Higher achievements.
Complete the game fully (all quests, secret rooms and animal kings)
All quests completed
Kill Trickster King
Kill all animal kings
Kill Gigantine
Kill Zombie King
Kill 50+ Enemies with Gravitron's Laser
Kill Lion King
Kill 1+ enemy with Piu-Piu
Kill Ooze King
Kill Queen Twin
Kill Scorpion King
Hard Mode Completed
Finish the game in less than 9 hours in Hard Mode
All secret rooms found
Kill Imp King
Held more than 30 000 Gold
Kill 200+ Enemies with Abu
Repair Gravitron
Complete 8+ quests for Dee
Pass Gigantine's Lair
Kill Gorilla King
Tame 30+ Enemies with Jezabel
Kill 50+ enemies with Abu
Complete 6+ quests
Spend 20+ hours on the game
Find 5+ secret rooms
50+ items found
Play 1+ hour
Complete 1 quest
Create Your Government List
Find 1+ secret room