You have 3 hearts. If you get hit by enemy or bullet, you lose a heart. If you run out of hearts, the game is over.
Your last heart regenerate if you don't get hit for a while.
Bosses don't have collision, only their bullets.
Hold square to shoot and move fast.
Hold X to shoot and move slow.
Press O to fire smart bomb, which clears all bullets within the blue circle.
Smart bomb recharges in around 3 seconds.
If the blue circle is the same radius as the green circle, the smart bomb is fully charged, and will not only clear bullets, but also kill all enemies inside the circle.
H pickups give you an extra heart, up to a maximum of 5.
P pickups increase your weapon power.
B pickups fire a smart bomb on pickup. These are mostly used for implicit tutorials of game mechanics.
Tips
Switch between X and square to control speed.
Use smart bombs to clear bullets whenever you need to. Often the game requires using the smart bomb, because many bullet patterns are unavoidable.
Use fully charged smart bombs to kill enemies that are unreachable with your normal shots.
Going for highscores, try all 3 difficulties and see which works best for you.
Analysis
For all of its visual intensity, this game seems well-designed and not unfair. You just have to learn the rules.
Screenshots marked with 🍒 are created by syltefar and are considered public domain, free to use for anything. If you want to, you can note where you found it and link to this page.