Here is the full list of all 50 Truxton achievements.
Upgrade your weapons one time
Turn the first boss in the game into dust
Eliminate the first boss without assistance
You have achieved your first of many losses to come
Play a hundred games
Get terminated a thousand times
Fire one million buillets of any kind
Defeat ten thousand enemies
Upgrade your weapons a thousand times
Upgrade any weapon to the max
Crush the spirit of life out of the second boss
Return the third boss to its maker
Put the fourth boss six feet under
Turn the fifth boss into shards
Deal with the sixth boss
Show the seventh boss its ending cutscene
Leave the eighth boss in the ocean
End the existence of the ninth boss
Give the tenth boss its resignation forms
Leave the eleventh boss in your tracks
Show the twelfth boss the path to redemption
Mangle the thirteenth boss beyond repair
Add the fourteenth boss to the pile of achievements
Disassemble the fifteenth boss
Steamroll the sixteenth boss
Pulverize the seventeenth boss
Return the eighteenth boss to sender
Make the nineteenth boss sleep with the robo-fishes
Slaughter the Final Boss
Eliminate the third boss without assistance
Eliminate the fourth boss without assistance
Eliminate the fifth boss without assistance
Eliminate the sixth boss without assistance
Eliminate the seventh boss without assistance
Eliminate the eight boss without assistance
Eliminate the ninth boss without assistance
Eliminate the tenth boss without assistance
Eliminate the eleventh boss without assistance
Eliminate the twelfth boss without assistance
Eliminate the thirteenth boss without assistance
Eliminate the fourteenth boss without assistance
Eliminate the fifteenth boss without assistance
Eliminate the sixteenth boss without assistance
Eliminate the seventeenth boss without assistance
Eliminate the eighteenth boss without assistance
Eliminate the nineteenth boss without assistance
Eliminate the final boss without assistance
Eliminate the second boss without assistance
Complete the game using only one credit
Complete the game using only one credit without assistance