lvl 32 no star.
Game: idle game, don't do anything.
You need to level up. 100 lvl = 1 star, 1 star + 110 levels = 2 stars, 2 stars + 120 levels = 3 stars etc etc...
After 6 stars there is no level limit.
The monsters: The monsters change every 10 level. Each monster type is harder and harder.
You get 1 gold by every killed monster.
The bonuses: You can buy xp bonus with gold. 10 minutes (1000 g)= xp x2 during ten minutes.
25 minutes (2000 g)=xp x2 during 25 minutes.
60 minutes (4000 g)=xp x2 during 60 minutes.
The bonuses aren't saved, so don't quit during a bonus.