For anyone looking to see whether this is hard, it's not at all. You unlock god mode for completing the game and then 5 levels in NG+. It's a total breeze with this and the secondary weapon you unlock for beating the game.
For me personally this only unlocked after getting S rank on all 9 levels in the main game, and then S rank on all 9 levels in the NG+ mirror universe of the levels.
The road map for this game would be:(Make sure to turn on auto fire in the settings before anyone starts)
Simply play through the story not going for any rank, checking the armory after each mission to see if you can improve your build. Use gun nut perk when unlocked, as well as protein bar too. Secondary I used chonker bombs when unlocked and then changed to Mighty Booster when I unlocked that and used that for rest of missions.
1. Void Prison
2. Planet Zandbak
2a. Krak'Bak
3. Bugga'veo
3a. Abandoned Tunnel
4. Aether Realm
4a. Station Derv
4b. KOLOS Prisoners
5. KOLOS 1
(You get an achievement after completing each individual level here)After beating the final boss you'll unlock New Game Plus via a portal that takes you to a mirror universe with the same missions only harder. Don't worry about this being hard, it is not. To make this a breeze, in the armory equip
Vark CRT and
Protein Bar on the first page, giving you a flying ai supporting you and longer mighty meter usages.
For your secondary weapon use
Void King Glove - this is op, use it non-stop whenever it's available every 5 seconds
Next, only complete these levels that are considered 'main missions' first. Once again don't bother with S rank at the moment, but have it in mind. I got S rank on the first 4 of these just by playing them here in NG+, but it's not an issue if you don't get them here, it will only save you having to play them again on NG+ at the later stage.
1. Void Prison+
2. Planet Zandbak+
3. Bugga'veo+
4. Aether Realm+
5. KOLOS 1+
(simply skip any mission that is not on this list for now)
(This also unlocks the 'Master of the Universe' achievement)
Once you have beaten these 5 levels, return to the portal at the start of the mirror universe map, and
you'll unlock god mode in the armory at the bottom called "Power of the gods". This makes you invincible and gives you infinite ammo, secondary usages and mighty meter. Makes getting S rank a breeze as you can just walk right whilst holding X to fire as well as spamming Y non-stop the whole level using the Void King Glove.
You don't have to watch it, but just as an example to show there's no need to worry about this one achievement tripping up your completion, here's a 30 second game clip of me just spamming Y with Void King Glove and God mode so you can see how ridiculously easy S rank is. Now that we've got God mode on, you can swap the Protein Bar for the movement speed boots if you so care, I personally didn't but I never used the mighty meter at all anymore due to not needing to with just spamming Y, so perhaps the extra movement speed will just help speed things along, just something extra I thought of while writing the guide.
So now go back to the original levels, playthrough each getting S rank using this tactic, you should get it first time with God mode on and just spamming Y with Void King Glove. You'll also unlock 'defeat a boss in under 1 minute' and 'finish a level in under 5 minutes' whilst doing these levels now if you missed them during your normal playthrough.
I personally did not have to farm bug enemies for the combo or anything like that some talk about in the forums, I simply 1st tried S rank on every level doing this. However if you don't quite get it yourself on Bugga'veo/Abandoned Tunnel, or their respective NG+ versions later on in the road map, go abit slower and let more tiny bugs spawn from the bigger enemies that releases them, in order to finish on more kills, and try your best to keep combos going. If necessary can even just stand there with God mode and allow an extra hundred odd to ensure S rank if all else fails.
1. Void Prison
2. Planet Zandbak
2a. Krak'Bak
3. Bugga'veo
3a. Abandoned Tunnel
4. Aether Realm
4a. Station Derv
4b. KOLOS Prisoners
5. KOLOS 1
After beating the final boss again, not sure if it's supposed to pop here and I just got unlucky or not. If it does, congrats, but if not it's completely fine and no issue.
Simply now go into the mirror NG+ portal and do the same again, S ranking these levels using god mode. If you've already S ranked some these NG+ ones from earlier then you save yourself having to do 'em again.
1. Void Prison+
2. Planet Zandbak+
2a. Krak'Bak+
3. Bugga'veo+
3a. Abandoned Tunnel+
4. Aether Realm+
4a. Station Derv+
4b. KOLOS Prisoners+
5. KOLOS 1+
This will complete S rank for all 9 levels on both sides (18 in total) and award the achievement.
I personally unlocked the 10,000 coin achievement before the final S rank, but had to replay level Bugga'veo+ a few times to unlock the 10,000 kills achievement.
Hope this helps, any feedback is appreciated.