Here is the full list of all 50 Aliens In The Yard achievements.
Make a combo of 5
Shoot down 50 saucers
Shoot down 150 saucers
Shoot down 1000 saucers
Shoot down 50 bosses
Shoot down 100 bosses
Shoot down 300 bosses
Kill 500 aliens
Kill 1500 aliens
Kill 3000 aliens
Throw a stick at the target
Make a combo of 10
Make a combo of 15
Earn 100,000 points using time bonuses
Stop 50 technology-stealing aliens
Stop 150 technology-stealing aliens
Stop 500 technology-stealing aliens
Spend 1000 hours in the game
Remove 100 plasma bogeys from your face
Remove 500 plasma bogeys from your face
Remove 1000 plasma bogeys from your face
Catch a plasma bogey in flight
Catch 50 plasma bogeys in flight
Catch 100 plasma bogeys in flight
Destroy 100 machinegun saucers
Destroy 500 machinegun saucers
Destroy 1000 machinegun saucers
Destroy 100 shotgun saucers
Destroy 500 shotgun saucers
Destroy 1000 shotgun saucers
Destroy 100 super shotgun saucers
Destroy 500 super shotgun saucers
Destroy 1000 super shotgun saucers
Shoot down a plasma bogey with another plasma bogey
Meet a boss for the first time
Shoot 1000 garbage cans.
Shoot gravi-cars 10,000 times.
Don’t catch a bogey at all in a single session
Lose on the first wave
Get the Untouchable and Loser! achievements
Allow the aliens to kidnap a grandma
Allow the aliens to steal 500 technologies
Allow the aliens to steal 1500 technologies
Throw and catch a lit cherry bomb
Fire 1,000,000 shots
Blow up a flying saucer with a cherry bomb
Smear 100 weapons with plasma bogeys
Smear 500 weapons with plasma bogeys
Smear 1000 weapons with plasma bogeys