Before doing this mission, you may want to check if you've done all sidequests for your homies. Take note that for Matt Mller, Ben King and Pierce, you have to choose the romance option for them as well to unlock their respective achievements. If you're using a male character, you may want to switch to a female character as well (or vice versa) since there's an achievement related to that.
When ready, meet Kinzie on the ship. You'll be reminded that you won't be able to return until you finish everything completely. When you're ready, save the game on a separate file. You'll then be asked to choose your team who will accompany you in delivering the key to the mainframe. Choose your team then enter the simulation.
You have to defend the truck from zin pursuers. Keep blowing stuff until you reach a blockade where you'll temporarily stop. Clear the blockade and continue forth. More enemies will appear and then Zinyak will remove your truck. Use your telekinesis to bring the key to the tower. Defend CID as tries to remove the forcefield in the tower's entrance. After successfully removing the barrier, pick up the key and head inside.
Once inside, you'll have to assist CID in inserting the key. Your first task is to disable the three breakers by stomping on them. After that, defend the key as it moves forward. There will be a lot of enemies firing at the key so do you best taking them out from platform to platform.
After a short while, the key's advance will be halted by a couple of suppression devices. Fight your way to those devices and disable them. Continue whittling down the enemy numbers as the key nears its destination. Finally, in the last obstacle, you have to destroy three relays. A warden will join the fray as well so take it out as you take care of the relays. After destroying the relay, continue killing more enemies until CID finally inserts the key.
Grand Finale (Part Two)
In the next part, you’ll be back in virtual Steelport. Head to the first portal and clear all enemies on the platform. Hold your position and defend the portal as a continuous stream of enemy reinforcements appear through their own portals. After succesfully defending that platform, head to the next portal with Matt. Repeat the same process and defend your own portal for a minute against continuous enemy reinforcements. Finally, head to the last portal.
There you have to kill 10 aliens first. After that, you’ll ahve to defend the portal for 2 minutes. Deal with the enemy reinforcements alone until the portal is successfully defended. Once Paul emerges, you have to escape the simulation before the time runs out. Keep moving and try all the marked portals. All the portals you’ll try will be locked so keep moving until you reach the last open one. Press A on the Saints Row screen after the short glitching sequence.
Grand Finale (Part Three)
Join your last team to kick ass in reality. You’ll only be using limited alien weapons here and you won’t have powers. Your health regenerates but you have to stay away from enemy fire for a while. Don’t be too aggressive or you’ll get shredded by enemy fire. Continue clearing the hallways until you reach the large room leading to the armory. Try to open the door only to discover it locked. One of your homies will attempt to open it so you’ll have to protect him/her. Enemies will become more aggressive at this point and will try to overpower you. Watch out for those murderbots and shield-generating CIDs. Once the door’s open head inside and change into the Iron Saint armor.
Grand Finale (Part Four?)
While going through the tunnel, evade the lasers. After a short while, the blast doors will be closed. You’ll have to land and find a way to overload them. While wearing the armor, you’ll have your powers from the simulation back however your main weapons is the plasma blasts powered by your suit. Clear the narrow corridor and overload the conduits in the end. Escape the area and you’ll be back in the tunnel. You’ll have to jump again and evade the debris until you reach the end.
You’ll finally reach Zinyak’s throne room. After the scene, it’s finally time for the final showdown. Move from platform to platform and attack Zinyak with your plasma blasts and power. Don’t undersestimate his laser cannons as they deal considerable damage per hit. He can also fire a volley of these so don’t soak up too much damage. In case you need to regenerate your health, run around the outer corridor beside the walls or just hide where his projectiles can’t reach you. Keep doing this until his HP is down by a large amount.
What’s a good boss fight without a challenge? Zinyak will stay in the middle platform and will be protected by a shield. You can’t do anything with the shield generators for now. Once your objective is updated, you’ll have to throw the self-detonating CIDs at Zinyak using telekinesis to damage his mech. Take note that you’ll have to do this while dealing with a continuous supply of zin reinforcements. Make sure that your telekinesis is not set to Arc Lightning element. If you do, you won’t be able to throw the CIDs without them prematurely detonating in your face.
After dealing more damage to Zinyak using his volatile CIDs, you’ll now be able to shut down the generators. You can’t destroy these but you have to press and hold Y to forcibly shut them down. Unfortunately, each generator is protected by a squad of murderbots. With shield-generating CIDs. Take note that they are also continously appear from zin portals so your window of opportunity between clearing the platform and before another murderbot wave is rather small. Fall back to the outer hallways again if you need to regenerate your HP. After the last generator is down, Zinyak will become vulnerable again.
Go all out and shoot the hell out of Zinyak to defeat him. Congratulations for completing the game!
The Iron Saint outfit will be unlocked
Mech Suit can be selected from the Phone Menu
Control the time of day from the ship's computer
You can now continue playing the game to complete the remaining collectibles.