>Items are written in the same order as the game's library.
>You don't need to complete Developer commentary to get the achievement.
>every item is listed and the way to get them is explained after each one of them.
>i'm not sure how i got every item in library. the ones that i don't know how to obtain will be left blank. other people can fill the blanks if they know how to obtain them.

BASIC - kill the yellow small enemies a few times.

HIBERNATER -

HOMER - kill the small enemies that chase after you a few times.

BOMBER - kill the big yellow guys a few times.

ARROW -

FREEZER - destroy blue stones that freeze you

SHIELDER - destroy them a few times (they create a yellow circle which it's radius increase until you start shooting at them.)

SPLITTER - kill the green splitter spaceship before destroying itself.

SPLITTED - kill the three small green spaceships after Splitter destroys itself.

BOOMER - destroy big yellow spaceships a few times. (there is another achievement for killing 5 of these.)

FAT BASIC -

CORE BOSS - Defeat the core boss

TURRET BOSS - Defeat the turret boss

BULLET BOSS - Defeat the Bullet boss

ASTEROID - pass through asteroids (or see them. i'm not sure about this one)

SOLID PLANET - drill through planets.

GAS GIANT - pass through gas planets.

GAS GATES - pass through blue laser gates that randomly spawn in gas planets.

A SUN - see a sun for first time.

RED SHIP - have a second player in your game.

GREEN SHIP - have a third player in your game.

YELLOW SHIP - have a fourth player in your game.

MOTHERSHIP - just play the game. this is you.

BACK PRESSURE - use B.P.B. it's generated when you are not firing your gun. (the big lasers).

CLASSIC MODE - play 'Classic mode' at least 10 times.

BOSSRUSH MODE - play 'Bossrush mode' at least 10 times.

ARCADE MODE - play 'Arcade mode' at least 10 times.

PACIFISM MODE - play 'Pacifism mode' at least 10 times.

COUNTDOWN MODE - play 'Countdown mode' at least 10 times.

NIGHTMARE MODE - play 'Nightmare mode' at least 10 times.

MARATHON MODE - Play 'Marathon mode' at least 10 times.

STARBITS - collect starbits. (the blue bits that scatter after killing an enemy)

GIANT LASER - see the yellow big lasers that shoot from right of your screen in an straight line for the first time (or a few times)

BARRICADE - shoot the pink glowing + shapes that get bigger the more you shoot them. don't
shoot them too much as they will fill a big portion of your screen and will damage you.

BLOBS - shoot the red circled bombs. they will start spinning when you shoot them and will explode if they come in contact with anything, or if you shoot them enough.

BLACKHOLE - just survive through a blackhole. it's obvious when you reach them. the background turns black and a siren starts playing.

DINOSAUR - kill dinosaurs in a blackhole. (there is an achievement for passing through a blackhole WITHOUT killing any dinosaurs.)

FROZEN - get frozen by the Freezers.

WIDEBAND - fully upgrade 'Wideband' in Classic Mode.

POLARSHOT - fully upgrade 'Polarshot' in Classic Mode.

CONTRA - fully upgrade 'Contra' in Classic Mode.

COHERENCE - fully upgrade 'Coherence' in Classic Mode.

FREQUENCY - fully upgrade 'Frequency' in Classic Mode.

MAGNETCOIL - fully upgrade 'Magnetcoil' in Classic Mode.

ELECROMAGNET - fully upgrade 'Elecromagnet' in Classic Mode.

ORBITAL - fully upgrade 'Orbital' in Classic Mode.

CLAYMORE - fully upgrade 'Claymore' in Classic Mode.

BASE ENGINE - fully upgrade 'Base Engine' in Classic Mode.

RADIOSHIELD - fully upgrade 'RadioShield' in Classic Mode.

WINGCANNON - fully upgrade 'WingCannon' in Classic Mode.

SPLIT LASER -

GHOSTSHIP - Die in a multiplayer game (and haunt your friends)

LASER PLANETS -

WORMHOLE - pass through a wormhole. they won't appear in Classic mode. try Arcade and other similar modes.

SPIN - use spin (Hold 'Drill' Button)

A PHONEBOX - collect the phonebox. it will appear randomly when you are playing. (i found it while playing classic mode.)

HELL CASCADE - it's a random event that happens. screen colors and music changes. just survive the event.

CHARGE LASER - fire a charged laser once or a few times. they will fire after you collect enough starbits.

INVINCIBADS - white enemies that won't die. shoot them a few times and give up.

FIREWALL BOSS - Defeat Firewall boss

TSOL CANNON - see a group of three cannons that appear from right of your screen and shoot purple lasers, for the first time and survive.

SPIKE CASCADE - it's a random event. screen colors turn negative and music changes. if you kill anything during this event, they will explode into a mass of deadly invincible slow spike balls that won't go away until the event ends. survive this event once or more. (PRO TIP: Don't shoot in this event)

RETRO - play 'Retro mode' at least 10 times.

ORB - a type of enemy. kill them a few times.

NAKED MODE - play 'Naked mode' at least 10 times.

REMIX MODE - play 'Remix mode' at least 10 times.

POWER UP PADS - pass through power up pads that appear inside solid planets.

PANDORA'S BOX - shoot and destroy the pandora box. there is a red text saying 'SHOOT' on top of the box. after being destroyed it will slowdown all bullet's speed.

FIREBALL - destroy the purple stones that generate some kind of shield that absorbs your lasers. Claymores are super effective against this enemy.

HELL MODE - play 'Hell mode' at least 10 times.

HELL SPLITTER -

HELL RAINER -

PEACEFUL MODE - play 'Peaceful mode' at least 10 times.

COMPUTER PART - collect a Monitor. it will appear randomly when you are playing.

ULTRA WEAPONS - purchase an ultra weapon after fully upgrading a weapon in 'Classic mode'.