that's what it is on steam version: you start with first 5 characters and have to unlock the rest (the same hold true on various trait and quest rewards as well)
really nice game (personally i called it 'right click necromancer') hope to see multiplayer implement (even a paid one is fine!) or on steam tho (i know it is unlikely, but well..) i can imagine it as a better agar.io kind of game
