Collectibles:
1 Artifact
4 Logs
1 Weapon Part
6 Upgrade Circuits

And here we enter the door to the elevator down to the last optional mission in Dead Space 3 after the shortcircuit minigame in Chapter 17.
The Suit Kiosk should be of no use, as your RIG should be maxed out by now, if not then now is a good time to max out the last remaining stats. Use the Bench to upgrade your weapons, build in some new mean circuits and then get going. Listen to the Audio Log (1/4) down here and get towards the next door to find a Text Log (2/4).

Finally enter the door to actually really start the optional mission. Grab the Ammo Clip and get through the next door to find yourself in a huge zero gravity zone.
Grab the 2 boxes and start floating and fly down towards the next bridge. Kill the huge Necromorph floating around here by shooting its 4 glowing tentacles. When hitting the main swollen yellow part it will explode and spit out one of these red explosive projectiles. There is another one of these huge Necropmorphs just deeper into the pit, also kill it from a good distance and you're set. On the second bridge across the room is a Text Log (3/4) just floating around in the zero gravity. Fly down to the lowest bridge, land, kinesis the Stasis Coating Weapon Part (1/1) from the opening over and open the door.

Open the 2 Lockers and proceed past the rather big skeleton to another zero gravity zone. Fly over to the special wall cabinet in the opening for a nice Upgrade Circuit (1/6), shoot the 5 traps and fly deeper down.
Really close to the bottom bridge floats another Text Log (4/4) in midair, get it, open the door, open the locker and activate the console to get another alien translation. It is for Warrior.
Enter the next door to a tunnel and prepare for 5 enhanced Leapers that attack all nearly at the same time. Now let your stasis refresh or use a stasis pack and then enter the next door.
There is a mean Alien Necromorph waiting for you behind the door, so you know what to do, use stasis a lot and cut off 2 of its limbs while moving backwards along the long tunnel room. Then let your stasis refresh again and get into the next tunnel with curve. Behind the next door is yet another Alien Necromorph with some Crawlers, so you should totally know what to do. But be careful, if you get into the room too far you will trigger 3 more enhanced Leapers that should better be dealt with after the Alien Necromorph is dead. Yeah, so refresh you stasis and kill the Leapers too (and the remaining Crawlers) and drop a Scaveger Bot at the Scavenging Point at the end of the tunnel before entering the door on the left.

Another Video explains another alien translation, this time for the word final. Open the 2 lockers and enter the next door to fly in zero gravity again. Don't destroy all the traps in here, only the traps closest to you and then slowly fly towards them. 6-7 Lurkers will come in and annoy you. But hopefully some of them get killed by the traps, but you still might want to shoot all the lurkers hiding in the dark as fast as possible. Always stay on the move and watch out where their shots come from.
Then find your way to the top bridge. Look back down into the depth and kinesis into the depth to fish for some goodies the lurkers left. Fly to the opening in the wall to get the Alien Artifact (1/1). Then play the hacking minigame to proceed. Get rid of the trap aimed at the hacking console first of course.

The next room has a Bench with an Upgrade Circuit (2/6) right next to it. Now the next room is interesting, there is another translation here, this time for Sacrifice.
So we have Warrior - Final - Sacrifice... what does this all mean? It is probably forshadowing Isaac's fate, but if you are playing this the first time I don't want to spoil anything for you, in case you replay the game and read this, well, you know how it all ends, don't you?

And there are 4 trapped Regenerators in here, but also a Scavenging Point and the Artifact Manifest to complete the mission. And most importantly the container with all kinds of nice things.

• 3 Upgade Circuits (3+4+5/6)
• 1 Serrano's Parts Box
• 1 Ammo Clip
• 1 Semiconductor set

Before entering the next room, make sure your health is filled and your stasis is refreshed, as this is getting tough now. Get the 3 lockers and enter the room of doom. A regenerator will jump at you right at the start, so cut off its legs and stasis it. Get up the stairs and 3 enhanced Leapers will attack. Probably not at the same time, but they are there. There is a ladder up here that leads down to a wall cabinet with another Upgrade Circuit (6/6), get it if you feel like doing so. When you climb back up the ladder a second Regenerator appears and you now have to shortcircuit the door to open it. As this takes some time it is very advisable to kill all 3 Leapers, then cut off the legs from both Regenerators and put them into stasis, maybe even twice for the first Regenerator after cutting off the legs from the second one, and only then start the shortcircuit minigame.
After the door is opened get through and you are away from the Regenerators and back in a zero gravity zone. Slowly fly up and let your stasis refresh, then land on the top bridge and enter the door. There are now 3 Regenerators waiting for you, just stasis them and run by. Enter the elevator door and ride back up.

That's it for this optional mission, the game continues now in Chapter 17, but here is the end of the Walkthrough, I hope you had fun playing the game (up to here) and reading my helpful musings.
Now go and complete the game! :)