Child of Eden

General tips:
Spam A
Forget Octo-lock
Go for smaller enemies first
Don't be afraid to take some hits, killing enemies is more important and theres a fair bit of health on the level.
Practise a lot

USE A CONTROLLER
*It's worth pausing and checking your progress against this guide
Again huge thanks to Cormac who worked out the start (for some reason I really struggled with this bit).

Wave 1-1:
4 enemies (4 hits each) = 8%
5 enemies (4 hits each) = 18%
5 enemies (4 hits each) = 29%
4 enemies (4 hits each) = 37%
4 enemies (1 hit each) = 39%
4 enemies (1 hit each) = 42%
4 enemies (1 hit each) = 44%
8 enemies (1 hit each) = 51%

Health Orb

8 enemies (1 hit each) = 56%
8 enemies (1 hit each) = 61%
8 enemies (1 hit each) = 65%
8 enemies (1 hit each) = 70%

Euphoria Orb

8 enemies (1 hit each) = 75%
8 enemies (1 hit each) = 80%
2 enemies (24 hit each) = 100%

Make sure you blast the final two enemies, they explode if you get too close so it's easy to think you have them when you don't.

Wave 1-2:
2 worms kill them quick along side the 2 hit enemies from above = 17%
1 purple worm = 32%

*with these purple worms you have to blast each section with the purple gun then blast each section with A

Health orb and them more 2 hit enemies come from above = 45%

Look Up!!

Once you see the purple worm dispatch of the 2 hit enemies = 58%
Kill the purple worm = 73%

Look Down!!

More 2 hit enemies
Health Orb = 87%
Final round of 2 hit enemies = 100%

Mid way boss:
By far the hardest part due to the end, when you do hit the orb spam A as much as you can!!

Blast red box's as quick as they appear.
10% when the Euphoria Orb appears
23% for first boss orb appearance
More red box blasting and a Health orb = 37%
53% for the second appearance (don't worry too much about the bullets better to hurt him)
Continue blasting the box's and enemies within
84% third and final appearance

*At this point you have to hit him hard and fast after a very short while use your bombs to finish him (I used two to be sure)

YOU MUST WATCH THE PURFICATION COUNTER: it's very hard to see but it will quickly flash 100% at the end

Wave 1-3:
The doors

This is annoying, blast with A everything quickly.
The easiest way to much up is to miss a red box on the doors be quick with them. The purple worm before the 5th door can be nasty don't be afraid to use your final bomb here to make sure he's dispatched quickly.

Be quick
Spam A

Kill door 1 = 19%
Kill door 2 = 43%
Kill door 3 = 55%
Kill door 4 = 74%
Kill door 5 = 87%
Kill door 6 = 100%

Final Boss:
Not too bad, during the first section make sure you hit all enemies before the boss orbs and you should sail through.
When he changes tidy up the moving squares they should be fairly easy.
The boss will move, keep blasting with A.
Again blast the box's quickly and by the time you get to the purple planet.

Move onto the planet part 1 simply hit with purple gun the batter with A.
Blast the squares with A
Next are some big worms nice and easy A blasting
Finally you should enter planet part 2 with 90%
Blast away quickly with A for your final 10%

Even knowing all of the above this was very hard to unlock in one playthrough.
Learn each section, hope and pray.

Hope this guide helps, any questions or complaints just let me know.

Good luck!!

This is very difficult, took me many many tries, but it definitely can be done.

General Tips:

I recommend using a controller to play, the kinect may be more fun, but you can fire faster with the controller.

Spam the A button like mad on a lot of these enemies, you need to kill them quickly before they dissapear off screen.

Always keep a sharp eye out for any enemies you may have missed, move the cursor around the screen to adjust the camera and keep a good look out.

*EDIT* The minnow like fish do NOT count towards your purification percentage, however, if you follow this guide, you should be able to nab the achievement easily

Ok, the following is a walkthrough of the trouble spots in the Matrix, where its easy to miss a few enemies:

1. After the tutorial area youll be inside a large blue area with many enemies in it. When the first purple worm appears, give it a few seconds then use a euphoria bomb (hit B), this will remove all the minnows and any other enemy currently on screen. Next, look up as a few more enemies will appear from here, once theyre dispatched look down...give it a few seconds and more schools of minnows will appear, wait for them to fully come into play then hit B again.

2. The next section will be where you face a grid that the boss will repeatedly move in and out of. This was the part where I kept missing enemies due to a simple mistake. Boxes on the grid will turn red, release a few enemies, rinse and repeat. The trick here is to kill the enemies first! If you kill the boxes it will jump to the next section (where the boss appears) and dissolve the enemies which will not count as you killing them. Remember, wait for the red boxes to spawn enemies, kill them, then kill the boxes.

3. Next area will the the "hallway" scene where you have to destroy the gates to make it through. Obviously if you fail to destroy a gate and it hits you, that will not count as you killing it, and will ruin your achievement. Around the 4th or 5th gate youll have a purple worm spawn, have your tracer ready, remove his shield and spam A as fast as you can, he will not be on screen long before the next gate hits. On the final gate youll have 2 smaller worms that fly away from you, again spam A on both worms, you only have seconds before they dissapear and the next gate appears, possibly ruining your achievement again.

4. The last trouble area is the cylinder type mini-boss in the next room, where you have to destroy several spheres that slowly open up to move on. The key here is to kill all the enemies around the cylinder before removing every sphere. At about the time the 2nd sphere opens up, several schools of minnows will have fully spawned in the background. Use your final euphoria (press B) here. Continue to kill the enemies and pick off the spheres, on the last sphere, 2 purple worms spawn, you MUST kill the worms before you kill the final sphere.

Everything beyond should'nt be too difficult.

Don't expect to get 100% on your first play through of the level, but as you keep playing, memorize where enemies spawn, give them no mercy, and remember to follow the guides on the troubled areas above.

Good luck, and happy hunting!

I just wanted to add to Darklights' solution, because I was stumbled a bit with the "Final Boss" part. I seemed to be only getting 99% on this part, so I counted all the enemies and here is the break-down.

After the 6-doors tunnel you arrive at the final boss. Disregarding the little blue fishes that are a distraction (but also a way to get points while perfect-octo-locking them!):

====== 4 red orbs area ========
1 blue snake = 1%
3 red enemies = 2%
1 blue snake = 3%
5 red enemies = 5%
1 blue snake = 8%
3 red enemies = 9%
1 last blue snake = 10%
*** At this point it's important to kill the last blue snake in time, otherwise u will not get two purple worms, but only one ***
2 purple worms = 15%
4 red orbs of the actual boss = 24%
======END of red orbs area = 24% (if you have 23%, that's not a problem yet, you can still make up for it later, this happened to me twice)

====== Moving red boxes area ======
This place is pretty self-explanatory, just kill all the boxes in time
====== END of moving red boxes area = 61%

====== Purple planet area ======
Here is where I was able to make up the last percent difference. Make sure to remove the purple boxes with the tracer before hitting the main target. But beware, the boxes fall back on it, so you have to clear them, then octo-lock, then again blast the boxes, then octo-lock the main thing. By performing octo-locks you can kill it up to the point where you will gain no more points even if you are octo-locking. The way I was able to get the last 1% (so from 71% -> 72%) was to just spam A until u see the percentage at 72%.
For me, without having 72% at this point it was impossible to clear the whole thing with 100%.
====== END of purple planet = 72%

The last parts are completely self-explanatory, spam A (or perform perfect octo-locks, if you are going for golden star)

16 red boxes = 80%
three snakes = 90%
last planet = 100%

Hope this helps! I know I was going crazy with this when I was going for the golden stars achievement.
Let me know if you have any comments/concerns! :)

The below solution is brilliant so Kudos to Darklights.

I just wanted to add that this achievement is made 10x's easier with a turbo controller using turbo on A.

One other thing. Make sure you DO NOT kill the Mid way boss the second time you see him. I played through it 6 or 7 times ending with 93% only to find I destroyed the boss before the third set of boxes spawn.

Good luck

This is are excellent guide for this level, for the Gold Star (100% + 800k) rank you definitely need some practice, but you can get the 100% on your first try. Just follow the video, this is very detailed and useful guide.

All credits goes to SajikoSakura

For this, you simply have to purify all enemies. This level is pretty straight forward, so you should have no trouble getting all of them.