Here is the full list of all 41 Robonauts achievements.
Find ancient armor
Kill the boss on level 2
Kill 3 enemies using the laser on level 8
Finish level 9 without killing any enemies
Jump between planets 300 times
Use all weapons
Find the hidden area on level 3
Kill 50 enemies
Complete 3 levels in a row without dying
Catch 5 healing bloobs
Catch 50 healing bloobs
Kill 10 enemies from a different planet
Kill 33 enemies from a different planet
Destroy 6 disruptors without getting hit on level 4
Destroy all the disruptors with the shotgun on level 4
Exhaust 6 nests
Kill 5 enemies without losing any HP on a single level
Kill 150 enemies
Interrupt 10 flying enemy attacks with a shotgun
Kill 20 nests mid-jump
Stand on every planet in the game
Complete 5 levels in a row without dying
Kill 7 enemies with a single plasma grenade
Hit an enemy 19 times without dying
Finish a level destroying only the marked enemies
Jump over a weapon drop 8 times on a single level
Let 100 bloobs disappear
Kill 4 enemies in a row using the stun gun
Stun 4 enemies at the same time with a stun grenade
Kill 5 enemies with a single shot from the rocket launcher
Set 5 enemies on fire with a single molotov grenade
Finish all the levels on hard difficulty
Destroy all the disruptors without getting hit on level 4
Each machine must retain more than 40% HP
Don't let the VIP lose any HP on level 10
Finish level 11 in less than 3 minutes 41 seconds
Finish level 12 without getting hit by a tower
Destroy all the towers without killing any enemies on level 12
Have an enemy die from a grenade after you died
Collect a gold medal on each level