It's an easy to pick up, hard to let go type of runner game.
On your way, collect same colored with your monster baits to level up. If you eat other colors, you'll lose level. If you hit 0, you'll fail. Eat monster which is level than yours to level up easier. Stay away from obstacles and over-leveled monsters.
If you surpass Level 32, your monster will grow to Stage 2. If you surpass Level 65, your monster will grow to Stage 3.
You can't pass Lava Ocean without losing level if your monster isn't at least at Stage 2.
You can't beat Werewolf if your monster isn't at least at Stage 3.