Here is the full list of all 30 Into the Belly of the Beast achievements.
Finally free! You managed to rescue your family and escape the beast! Happiness awaits!
You successfully beat Act IV
You successfully beat Act I
You successfully beat Act III
You successfully beat Act II
Every parent has a favourite.
Octokay defeated
The Glutton defeated
The Twins defeated
Gallerta defeated
Nothing escapes your greedy eye. You are a true collector
You collected your first health upgrade.
You managed to find all monsters in the bestiary
You engaged in combat with at least 50% of all the beasts inhabitants
You played for at least 8 gaming hours.
Successfully end your playthrough by mostly eating green DNA (80%)
Meat and fishballs. End your game by eating mostly purple DNA (80 %)
Why hunt, when tasty food presents itself? Congratulations! You're a cannibal.
You managed to defeat 100 enemies!
Beat the game without restarting a single stage.
Beat the game, without having died a single time. Including checkpoints.
You managed to defeat a boss without ever taking damage
You managed to defeat a boss with only 10% of your own life left.
You managed to end a game stage in full health
You managed to defeated a boss, but managed to die anyway. Well...
You died the true death two times in succession, on the same stage
You successfully rescued all of your offspring.
Two in One
Three in One
Four in One