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