Child of Eden

Here's my guide for gold stars, which is 800k and 100%. This is the version with commentary, explaining what I'm doing and generally why I'm doing it. I've also uploaded versions without commentary, which should be linked on the video page.

The most important thing to remember is to keep your perfect multiplier going! The multiplier only counts for octa-locks, meaning you'll get minimal points for spamming. For gold stars, you'll want a combination of octalocks and spamming, but if you're not going for gold stars, it's best to always try octalocks, even if the enemy is about to get away. Your purification percentage takes the hit, but you get a few more points out of it.

Points are abundant in Journey; even using a euphoria, you should still be able to hit 800k before the bonus kicks in. However, this is a long level, and endurance is going to be the real factor.

Also, if you're having trouble with octalocks, turn down the sound effects in the main menu. I dropped it to about 20% and the beat was very clear for me.

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 800k in a few tries. Just follow the video, this is very detailed and useful guide.

The easiest level to get 800k, but the longest. If you know what to do (follow the video), you can get about a 1,000,000 in the end on you first try.

Also, you should know how to make octa-locks (perfect 8x hit in the rhythm of music), without octalocks you do not succeed.
And, you should get and save 3 euphoria at the end of the level - this gives you 100k. Without this bonus get this achievement will be much harder.
Again, just follow the video and don't forget about gathering and saving euphoria and, of course, octalocks.

All credits goes to SajikoSakura