Level 28 is beatable without the premium upgrades; you just need to lose a couple times to know when to preemptively use your spells before the shamans appear. Level 29 is most definitely impossible without the premium upgrades from my experience; can't even get remotely close.
This game came out a month or two ago. Maybe one or two slight differences, but ultimately another games8 game where they change a couple things and introduce it as a completely new game under a different title.
is unlocking outfits really the only purpose of collecting coins? Most games with stores have things you can purchase that aren't completely useless...
 "Bit Battles"){kind=icon}
 "WreckRoad"){kind=icon}
 "Goblins at the Gates"){kind=icon}
 "Fiqa Dragoons"){kind=icon}
 "Dead Paradise 2"){kind=icon}
 "The Bravest Hunter"){kind=icon}
 "Heat Rush USA"){kind=icon}
 "Rocket Pets"){kind=icon}
 "Extreme Road Trip 2"){kind=icon}
 "Generic Tower Defense"){kind=icon}
 "Questopia"){kind=icon}
 "Construction Tycoon"){kind=icon}
 "Super Trail"){kind=icon}
 "Moto Trial Fest 3"){kind=icon}
 "Monster Bastion"){kind=icon}
 "No Cleaner"){kind=icon}
 "Trucksformerz"){kind=icon}
 "Zombies Mayhems"){kind=icon}
 "Papa Louie 2: When Burgers Attack!"){kind=icon}
 "Bois D'Arc"){kind=icon}
The whole game is definitely beatable without premium items.