Here is the full list of all 25 GRIDD: Retroenhanced achievements.
Survive your first Boss Fight
Gain a x32 multiplier in Arcade Mode
Gain a x24 multiplier in Arcade Mode
Destroy the first defense
Hack your first Backdoor
Defeat the Facehugger
Access the Mainframe
Complete the Arcade Mode
Complete the Arcade Mode without using any Backdoor
Charge the shield to maximum
Charge the weapon to maximum in Endless Mode
Collect 100 power-ups
Annihilate Mainframe defenses
Kill 100 enemies
Make 100 bullets bounce
Destroy 200 fragments
Complete the first Mainframe Sector
Access the 10th Mainframe Sector
Hack a total of 262.144 Kb
Hack a total of 524.228 Kb
Hack a total of 1.048.576 Kb
Access the 5th Mainframe Sector
Gain a Backdoor in Endless Mode
Survive at least 5 minutes in Endless Mode
Survive at least 10 minutes in Endless Mode