Here is the full list of all 44 Secret Agent HD achievements.
Collect over $1000000 worth of bonus items
Finish Episode 3
Collect SPY letters in wrong order
Get maximum rapid fire
Stack two barrels, one on another
Catch 50 hidden coin bags
Collect 100 tombstones
Get confused and slowed down at the same time.
Kill an enemy while wearing a jetpack
Kill 50 Ninja's
Finish Episode 2
Use the teleporter 50 times
Disable laser grid 20 timesCHIEVEMENT_DESC_23_16
Collect 25 toothbrushes
Die in water
Finish Episode 1
Collect All Magnifiying Glasses in any episode
Finish a level with an extra key in your inventory.
Finish any level with a perfect score
Finish any level
Collect all SPY letters in the right order
Finish Episode 4
Complete any level without killing any enemies
Finish any level in under 60 seconds
Hold 6 keys in your inventory at once
Destroy 10 mecha-spiders
Finish any episode on HARD with 35 ammo or more
Collect every flag in the game
Blow up enemy with a Dynamite
Destroy 10 tombstones
Finish 5 custom maps from the Workshop
Spend at least 60 seconds under the water
Complete any episode without taking damage.
Complete any episode in one session without loading.
Life is better in the hot tub.
Destroy crawler bot while in the air on medium or hard difficulty.
L10 without killing any enemies and with a perfect health.
Complete any episode on hard mode.
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Collect all island treasure.
Complete all achievements.