Here is the full list of all 27 Sky Force Anniversary achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Finish a stage with your health lower than 5%.
Rescue 500 people.
Enter the tournament.
Use 3 different power-ups in a single game.
Destroy at least 15 enemies with one Mega-Bomb.
Ram through an enemy wave with your Energy Shield.
Burn through 10 enemies with your Laser.
Destroy all enemy towers on Stage 5.
Use any 5 power-ups in a single game.
Destroy 2 500 enemies.
Earn 10 medals.
Destroy 1 000 enemies.
Rescue 100 people.
Destroy the lighthouse without touching it.
Destroy 10 000 enemies.
Rescue 1 000 people.
Earn 50 medals.
Earn 100 medals.
Collect 100 000 stars.
Collect 200 000 stars.
Save 20 000 stars in your bank.
Save 5 power-ups at the end of the stage.
Rescue your friends 20 times.
Rescue 5 VIPs.
Find all the cards.
Collect all the stars from Stage 3.
Complete Stage 8 without using power-ups.