Here is the full list of all 50 Pewt 'em Up! achievements.
Destroy 100 enemy drones.
Clear a stage without being hit once.
Destroy 100 asteroids.
Destroy 10 enemy drones.
Destroy 1k asteroids.
Destroy 10k asteroids.
Destroy 1k enemy drones.
Destroy 10 enemy ships.
Destroy 100 enemy ships.
Destroy 500 enemy ships.
Destroy a battleship without the Silver Wing.
Destroy a bumper ship.
Destroy a divider ship.
Defeat Varik Gorr.
Collect 1k credits.
Collect 10k credits.
Collect 50k credits.
Destroy 10 asteroids or enemy ships by ramming them.
Destroy 100 asteroids or enemy ships by ramming them.
Destroy 250 asteroids or enemy ships by ramming them.
Beat the game in Rookie or Cadet Mode.
Beat the game in Cadet Mode.
Beat stage mode twice.
Beat the game in Ace Mode.
Buy all Weapon upgrades in the shop.
Buy all Reloader upgrades in the shop.
Buy all Armor upgrades in the shop.
Buy all Shield upgrades in the shop.
Buy all Recharger upgrades in the shop.
Buy all Ship Parts upgrades in the shop.
Buy all Items in the shop.
Buy all available upgrades in the shop.
Hatch the egg.
Level up Egg-kun.
Use the bomb for the first time.
Self-destruct your ship by using the bomb.
Clear a stage without shooting once.
Watch the credits until the end.
Watch the post-credit scene.
Unlock the Valkyrie Type MA.
Unlock the Silver Wing.
Collect your first quartz fragment.
Collect 1k quartz fragments.
Collect 5k quartz fragments.
Achieve a score of at least 9001 in endless mode.
Achieve a score of at least 100k in endless mode.
Achieve a score of at least 250k in endless mode.
Achieve a score of at least 1M in endless mode.
Enter the sacred code in the main menu.
Unlock all achievements.