Minimon

Start an adventure in a world full of monster hunters!
Plagued by a strange disease, the continent of Chroma is in panic, and a strange turn of events will turn you - a small kid - into a powerful monster hunter, capable of tame even Ulmaxia, the dragon king!

• Customize your own monster hunter with tons of clothes, weapons and skills!
• More than 300 different monsters to train!
• Play either offline single player, local multiplayer via split-screen or online with up to 500 players per server!
• Tons of quests, secrets, and unlockable stuff!

Source:

Steam Store Description