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