Here is the full list of all 41 Defend the Highlands: World Tour achievements.
Kill 10,000 enemies in total
Fully upgrade a tower or your Scotsmen
Kill 100 enemies with fondue hoses
Heal 200 HP with shrines
Kill 100 enemies with whisky bars
Kill 100 enemies with drop bears
Kill 1,000 enemies with Alfredo
Kill 250 Japanese enemies
Complete an epic length skirmish match
Complete a skirmish match against all enemies
Kill 2,500 enemies in total
Kill 100 enemies with turnip turrets
Kill 100 enemies with Donald Bradman
Kill 100 enemies with haggis catapults
Kill 100 enemies with porridge cannons
Kill 100 enemies with golf balls
Kill 250 American enemies
Heal 200 HP with Buddha
Kill 250 Australian enemies
Kill 100 enemies with Julius Caesar
Complete a skirmish match on impossible
Kill 100 enemies with Cleopatra
Have £1,000 at once
Complete a skirmish match on hard
Have 60 Scotsmen on the field at once
Kill 100 enemies with Abraham Lincoln
Kill 250 Egyptian enemies
Complete a skirmish match on medium
Have 45 Scotsmen on the field at once
Complete a skirmish match on easy
Hold 6 oat fields for 2 minutes
Kill 100 enemies with Joan of Arc
Kill 250 Italian enemies
Kill 500 enemies in total
Kill 100 enemies with Alfredo
Fully upgrade a stat
Have 30 Scotsmen on the field at once
Kill 250 French enemies
Have 2,500 porridge at once
Kill 100 enemies with porridge bowls
Kill 100 enemies in total