The only mini-game thing we have is KOTH.
A PVP game made to test your PVP skills in a limited space , it is quite fun and rewarding.
Though that's the only one we have.
I think that after you finish the game it gets boring.
PVP is only fun for some time , maybe there could be challenges scattered around the map like a mini-game where you could fight mobs until you die.
Earning points to buy some new items that are exclusive to the point shop.
Those items would grant a health boost and defense boost or attack boost.
It would add a flare to the game in a way.
Though it might not fit into the game style and ruin the game in a way I worry.
But I think it would be a nice feature to add in.