Here is the full list of all 21 Landflix Odyssey achievements.
Defeat Doctor Banner
Defeat the Demodoctor
Defeat the Undead King
Defeat the Evil Queen
Defeat KingPink
Defeat Yubi
Defeat Salamandra
Defeat Pavos
Defeat Twight
Defeat the Akler
Finish Peculiar Stuff's "The School" level, without getting discovered
Reach the top of a certain wall
Ride a dragon across the sea
Defeat the Evil Queen's Black Knight 20 times in a single game
Completelly destroy a certain vehicle
Slay over 100 turkeys
Beat the drugged level in Going mad
Kill the same zombie over and over 7 times in The Standing Zombies
Grab every single coin
Grab every single blue ticket
Beat every "Special features" level