Here is the full list of all 35 Adventure Time: The Secret Of The Nameless Kingdom achievements.
Choose Lullaby Princess to rule
Choose Slumber Princess to rule
Choose Nightmare Princess to rule
Find all thump shards / spare thumps
Find everything in the game
Complete the Trading Game quest
Party in the Rave Cave for 11 minutes and 12 seconds
Find all five baggies
Complete the Door Repair quest
Find every Gunter cave
Break the pot breaking record
Stun 5 enemies with a single Bananarang
Complete the Dungeon Drama quest
Complete the Fear Temple
Receive every curse
Kill an enemy after both Finn and Jake have attacked it
Kill a Lub Glub using Flambo
Complete sword training
Beat Starchy's Graveyard Fun Run
Complete the Dream Temple
Talk to Stanley five times
Buy any trail mix
Complete the Terrible People quest
Lie to Marceline
Complete the Cinnamon Fun! quest
Chop down 999 bushes
Store a Convict Fairy in a baggy
Find a thump shard
Complete the Song Temple
Use Grabby Hand on a Pie Fairy
Find a gum globe
Complete the Love Note quest
Buy something from Choose Goose
Complete the tutorial
Beat the game with 3 thumps, without upgraded sword, shield, or armor