This guide will list the achievements for Intergalactic Bubbles, and detail one strategy to 100% the game. This isn't the only way to win, but it's the way I used. Hope it helps others to 100% the game's achievements.

The different galaxies' only differences is that they unlock new colors of balls.
You start with red, dark blue, and green.
Upon completion of each galaxy, you unlock 4 new colors of ball in order: Yellow, Light Blue, Purple, and Orange.
This does not make the game noticeably harder, unless you happen to be color blind, in which case it will make the game impossible should the ball unlocked match the type of color blindness you have.

NOTE:
Due to the game's starting colors being red, green, and blue, anybody who has red-green color blindness will find even the first galaxy impossible and frustrating (ditto for anybody with total color blindness).
Those with blue-yellow color blindness will likely be head-desking at the second galaxy, which introduces yellow balls.

Achievements can be divided into 2 groups: the survival achievements, and the perfection achievements.


Survival achievements are automatic for getting through all 50 levels of each of the sections of the game, or "galaxies". They are as follows:

Explorer of Stars
Survive all Milky Way levels

Explorer of Light
Survive all Andromeda levels

Explorer of Awe
Survive all Orion levels

Explorer of Shadows
Survive all Medusa levels

Explorer of Creation
Survive all Pillars of Creation levels


Perfection achievements are gained by getting all 3 stars in all levels of each galaxy. A perfect level is obtained by using no more balls than is first listed at the beginning of each level. You can use up to that number, but if you use more than indicated, you'll lose stars. The level can still be completed, and can be replayed until perfected. You can also go back to previous levels to gain perfect on them later.

Defender of Stars
Get 3 stars (Perfect) in all Milky Way levels

Defender of Light
Get 3 stars (Perfect) in all Andromeda levels

Defender of Awe
Get 3 stars (Perfect) in all Orion levels

Defender of Shadows
Get 3 stars (Perfect) in all Medusa levels

Defender of Creation
Get 3 stars (Perfect) in all Pillars of Creation levels

Over the course of the game, you will use the stars you gain from levels to unlock ranks in various stats, which will improve your game. You can easily increase or decrease stats at no penalties, which gives you great freedom to experiment. This guide, however, will focus on 3 groups of stats: Bombs, Shields, and Energy.

Unless otherwise noted, most stats initially cost 5 points to unlock and increase linearly (5, +10, +15, +20, etc...). Stats have 1, 5, or 10 ranks total.


1. Energy Bar
The Energy Bar governs how often you can use the special balls, and costs 1 star to unlock.
This is required for all other upgrades.
Energy bar only has 1 rank (there is, however, a whole branch of the stat tree devoted to improving this, detailed later).


2. BOMBS
Bombs are one of 3 types of special ball you can use during gameplay.
Unlocking bombs requires 5 stars.
Bombs can bounce off of walls, and explode when they touch another ball. This destroys a number of balls around the explosion.
Increasing Bomb radius is a must, and has 5 ranks.
You will want to max your Bomb Radius, which will cost 75 points total to max.
I try to max this as early as possible.
Each use of a Bomb uses 1,000 energy.


3. Shield
Shield is what protects you temporarily from balls that get past your defenses, allowing you to recover from an otherwise fatal lapse in ball-blasting. This can be further divided into 2 stats:

Max Shield Lets more balls pass through your shield. This can be invaluable, and is a good second priority to bombs. I have finished several levels by sacrificing the last few balls to my shields.
Max Shield has 5 ranks, which will cost you 75 points total to max.

Shield Regeneration Can be useful, but usually will not be enough when a lot of balls are too close to blast. Raise this in mid to late game.
Shield Regen has 5 ranks, which will cost 75 points total to max.


4. Improving the Energy Bar
This area is where most of your points will actuallly go, and is the third priority after Bombs and Shield.
Alternatively, you could focus on this as a second priority over shields.
This part of the tree governs how many bombs you can lob, since it raises max energy and energy regen.

Starting Energy This deals with the amount of energy you start each level with.
At the endgame, you'll be 8/10 ranks in this and start with 4,000 energy.
This will cost you 180 stars, total.

Maximum Energy This increases the max amount of energy you can have at one time.
At the endgame, you'll have 8/10 ranks in this and your energy bar will max at 5,000 energy.
This will cost you 180 stars, total.

Energy Regen The amount of energy you regenerate per second.
Max this at 5/5 ranks, for 75 stars.
At max power, you will regenerate 5 energy per second.

Energy per Ball Increases the base amount of energy you regenerate after dropping detatched balls into your shield.
Max this at 5/5 ranks, for 75 stars.
At max power, you will increase the energy gain by 5 points per ball. This may not seem like much until you drop 30 detatched balls into your shields in one go. You will be glad to have this on many levels.

This is mostly just a consolidation of the previous section, for ease of use.

1. Energy Bar
Ranks: 1/1 (1 star)


2.a. BOMB
Ranks: 1/1 (5 stars)

2.b. Bomb RADIUS
Ranks: 5/5 (75 stars)


3.a. Maximum Energy
Ranks: 8/10 (180 stars)

3.b. Starting Energy
Ranks: 8/10 (180 stars)

3.c. Energy per Bubble
Ranks: 5/5 (75 stars)

3.d. Energy Regeneration
Ranks: 5/5 (75 stars)


4.a. Maximum Shield
Ranks: 5/5 (75 stars)

4.b. Shield Regeneration
Ranks: 5/5 (75 stars)


Total Stars Used
741 of 750 stars total, with 9 stars left over (enough to play around with 1 or the other 2 ball types, perhaps)