Here is the full list of all 28 Tumblestone achievements.
Complete World 2.
Reach rank 25.
Solve Puzzle 2-8 using 44 moves.
Empty the board in Marathon.
Win an online Battle match.
Win an online Tug of War match.
Win an online Puzzle Race match.
Win a Puzzle Race match using a modifier.
Complete World 1.
Complete 25 quests.
Win a Tug of War match against 3 Nightmare bots.
Solve a 3-star Practice Puzzle.
Empty the board in Heartbeat.
Complete World 3.
Complete World 4.
Complete World 5.
Complete World 6.
Complete World 7.
Complete World 8.
Complete World 9.
Complete World 10.
Complete World 11.
Complete the Story Mode.
Win a Battle match against 3 Nightmare bots.
Get a score of 333 in Heartbeat.
Get a score of 500 in Infinipuzzle.
Get a score of 333 in Infinipuzzle using a modifier.
Get a score of 1,234 in Marathon.