Here is the full list of all 18 BoneBone achievements.
Buy 20 arrows for bow
Buy 5 archers
Kill 100 skeletons in one session of the game
Survive more than five waves
Hit at least once
The first time in a game
Buy 1000 hp for wall
Kill 15 skeletons in the first wave
Survive more than twenty waves
Buy Gun for player
Buy 1 archer, 1 gunman, Tower level 3, Gun (player), Tower Gun, Crossbow
Earn more than 5000 gold
Buy Crossbow
Buy tower level 3
Save 10 refugee!
Buy weapon with magic modificator!
Buy legendary weapon!