Really fun idea! keeping the gameplay part shot at the start and buying mana to gain more play time is a really good design in my opinion, lets a new player experience the gameplay loop fast first time.
My only critic would be that the ending was a little abrupt, i think i played 3 levels and then stickolas grew legs and thats it XD.
As a suggestion i would try some really subtle screen shake, and maybe a "combo bar" mechanic that depletes with time, that would encourage the most competitive players.
Anyway, gameplay is solid and has a lot of potential, congrats!