Pets, potions and magic
1) You could make pets like: Flying Fishes, Dragons, Fire Salamanders, etc. To get a pet you could tame one (with a special object) in their habitat. You could take care of your pet and make them battle other pets in collisiums and earn gold if you win.
2) Potions could be for anything like life elixers or mana elixers, potions could also be for changing a characters form to an animal or a mythical cretures, etc.
3) Magic could be spells that you can learn from buying a spellbook in the shop. Examples for different types of spells: Water Spell (a water sprout damages the monster/ gamer), Fire Spell (explosions occur on the monster/character), Healing Spell (green light can fall to your character) etc.
-
Eoin commented
maybe you could use the eggs from the Easter event to tame a certain type of pet (Fire egg for a dragon, water egg for flying shark, air egg for a bird, Earth egg for... some Earthy pet XD)