The Version 20.0 Title update for Bloons TD 6 has 9 achievements.
Purchase a Trophy Store item
Complete an Odyssey in under 1 hour
Complete an Odyssey
Complete a Hard Odyssey
Complete all 3 difficulties of a single Odyssey
Complete 12 different Odysseys
Complete 50 Odysseys
Complete 100 Odysseys
Complete an Odyssey without a Hero