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