Here is the full list of all 40 Zolg achievements.
Complete the game with 6 or less health.
Complete the game with 7 or less health.
Complete the game in 60 or less minutes.
Kill the final boss.
Get at least 4 health powerups.
Get the shield powerup.
Kill the fifth boss.
Get the speed boost powerup.
Kill the fourth boss.
Kill a defender.
Kill the third boss.
Get at least 3 health powerups.
Kill a stalker.
Get at least 2 health powerups.
Get the strength boost powerup.
Kill the second boss.
Kill a quad shooter.
Get at least 1 health powerup.
Kill a crawler.
Get the charge shot powerup.
Kill the first boss.
Kill an orbital.
Kill a bouncer.
Complete the game with only 3 health.
Complete the game with 4 or less health.
Complete the game with 5 or less health.
Complete the game with 800 or less shots fired.
Complete the game with 1200 or less shots fired.
Complete the game with 1500 or less shots fired.
Complete the game with 20 or less deaths.
Complete the game with 5 or less deaths.
Get all 5 health powerups.
Complete the game in 40 or less minutes.
Complete the game in 20 or less minutes.
Kill the first boss without getting hit.
Kill the second boss without getting hit.
Kill the third boss without getting hit.
Kill the fourth boss without getting hit.
Kill the fifth boss without getting hit.
Kill the final boss without getting hit.