Here's a temporary strat I'm going for now. EDIT: Updated 30th October.
Mutant Virus Guide for Level 4
1. Room 1
Go straight for SG gun (Red 0) on top.
Clean around the edges, and then work on the inner room until done.
Its unfortunate to die on this room with the SG, as you will lose it, and it gets much harder without it.
Go to Room 2.
2. Room 2
Go straight on top of the room for the Green 0. Swap it it with the SG gun. Go to Room 3.
3. Room 3
Put Green 0 on lower virus spitter. Get the Blue 1, and put it on top of the upper Virus Spitter, and if possible a little bit left to it, as it shoots to the right, making it more effective.
Go back to Room 2.
4. Room 2
If you have a low life bar from flying through all the virus, then die once on purpose to not lose your SG. When you start with a new life with a fresh re-filled lifebar, and a few second shield, grab the SG gun and shoot yourself a little blue area to stay in, and work from here to clean the room. Its a manageable room, but be very careful with the SSVs that shoots. If you manage to keep your SG that is ideal.
Go to Room 3.
5. Room 3
If you still have the SG gun do your best to clean the room. If you don't use the SF and cross your fingers you can pull it off. This can be a tough room, but with some luck and persistence you can manage, even with the SF. Important notice that the SVV brings a trail of viruses. I think its best to do the left side of the room, upper and lower level, and then shoot clear the tunnel. Then hurry and fly to the right side of the room. Take care of the virus, and from distance try to shoot any viruses back in the tunnel, without triggering the SVV.
When the room is cleaned go to Room 6.
6. Room 6
Immediately, quickly, go straight for the Green 1 and put it on top of the virus spitter in the middle of the room. If you still have the SG it will swap. Its good if you can keep the SG, so try to not die with it on you.
7. Stopping any core breakouts
Breakouts happen at random, and in random rooms, and is one of the hard features of the game. The first breakout starts approx after 8 minutes, and after each minute another breakout starts. Tthe room turns green and thats a breakout. When all the rooms has had a breakout and are green, they later after each minute turn into CORE BREAKOUTS. The room will be then green and will blink. Now its time to take them seriously. You have 4 minutes from the the first room starts blinking, and if you fail to attend it the game will evacuate and you'll game over. If you find this difficult to juggle while trying to clean a room, it can be helpful to use a timer.
After cleaning the third room, you'll likely have one or two core breakouts going. Go to these rooms and deal with them. To deal with a breakout simply fly to the room, shoot a little into the room until the room gets neutral again(the room looks like a mix of blue and green pixels on the map), and then you can leave for now. From now on you have to take care of the core breakouts after each room you clear.
8. Back to Room 6
After dealing with the breakouts you can go back to Room 6. If you had luck the only core breakout was in Room 6 and didn't have to leave.
If you still have the SG you can finish the room quickly.
Go to Room 5.
9. Room 5
Take the Blue 0.
Go to Room 4.
10. Room 4
Put the Blue 0, put it on the virus spitter on the right side of the room. Its possibly preferable to put it a little bit to the right of it too, as this CM spreads vaccine to the left.
Go to Room 7.
11. Room 7
There's another SG here if you have lost your old one, but make sure you have as much lifebar as possible before taking it. Die once if necessary to get a full life bar since it'll be easier to keep it. You can probably choose to do Room 7 or 5 now. If you have to do attend a core breakout you can choose Room 5, but otherwise just cleaning Room 7 is fine. Clean the room.
Go to Room 5.
12. Room 5
You can choose to grab the shield in Room 4 on your way, but if you still have the SG thats better.
If you use the SG: Go around the edges first, then move into the inner room carefully. Observe the SSVs. They can be difficult to avoid in here, but if you look closely they only have 3-4 different patterns, so if you memorize them you can effectively avoid being hit by them.
If you use the the shield: You can go immediately into the inner room where all the SSVs are, shoot yourself a safe blue pocket, and try to clean it as much as possible when you have the shield, and hope to clean the inner room. Then work around the edges.
13. Room 4
Final room, and the toughest one to clear. Its good to take out this last so you don't have to worry about anymore core breakouts.
This room has two virus spitters and even a Proxy-SSV that will shoot when you are near it. You should now have one CM on the right virus spitter, and ideally a SG. If you never used the Shield and don't have the SG you can use that for protection 8 seconds too.
I've dealt with this room by trying to clean up the left side of the room first, then go from top to the right and carefully take out more and more of this room.
If you have the SG you can shoot the walls around corners without triggering the Proxy-SSV. When the right side of the room is done, go back to the left virus spitter. It can be tricky to shoot the viruses while the virus spitter spits out more, but sooner or later you'll make it.
When you've cleaned this room this the whole level is cleared.
Edited: 10/30/2016
at 06:19 PM
by Svankmajer