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The Mutant Virus: Crisis in a Computer World






Genre: Arcade/Puzzle

Publisher: American Softworks

Total time played: 40 Hours

Short review: It starts off as an arcade game and very quickly becomes a puzzle game that appears to be more luck than skill. Well known to be one of the most difficult games on the NES.

Interesting links related to The Mutant Virus

This Random Game Selection…

After finally beating Destination Earthstar I was hoping the NES God’s would throw me an easy game. Instead I was presented with a game that if it weren’t for the website NintendoAge.com I would know nothing about. What I learned reading about the game is that it is hard and there doesn’t seem to be a consistent strategy to beat the game. In fact, this post is keeping track of all people on the site that have beaten the game, to my knowledge it is the only game on the site that is tracked this way. As of this writing in 2018, only 7 of the 30k+ members of the site have beaten the game. I’m sure the game has been beaten by way more people than this, but, let’s just say, this information really intimidated me.

What is the game about?

The game is about a computer virus that is taking over a computer. Your job is to shrink down, go inside the computer and kill the virus.


Blue is good, green is bad and the black dots are what causes the virus to expand.

If This is True it is Super Cool

When trying to find a pattern for the way that the virus expands I ran across a video about a 1970’s computer program called “The Game of Life” where a programmer named John Conway made a program that showed how it would be possible for non-intelligent life to expand with just a few simple rules.

After watching the video I am pretty sure the game designers for The Mutant Virus used that program for inspiration. The virus spreads so fast that it would be impossible to test the theory without using an emulator to slow down the frame rate, but, either way, the use of this 1970’s program and thought experiment makes the game way more interesting.



B button – Acts a thruster, propelling you forward in whichever direction you are facing

D-Pad – rotates your character in place if you aren’t moving, changes directions if you are moving.

A button – this shoots your gun, holding the button acts as a rapid fire.

B + Up – Turbo boost which moves your character forward at a high speed

B + Down – Slows your character to a stop almost instantly

Select – Rotates through your weapons (see below for more info)

Start – Pauses the game


SF – Short Fire – shoots your weapon just a few feet in front of you. Handy to use if you are directly on top of the virus.

LF – Long Fire – shoots your weapon across the screen for attacking virus that is far away.

AU – Auto something?? – Seems to shoot across the screen until it comes in contact with a virus. Seems to be more handy than SF and LF.

SG – Super Gun – you won’t get this until level 3. This gun is incredible, it bounces off of walls and seems to clear out the virus much quicker than other guns. But, if you lose a life you lose the gun.

CM – Counter Measure – These weapons are scattered throughout rooms in each level and are displayed as horizontal tubes with 0’s or 1’s on them. These act as a bomb that continually ejecting antidote to fight the virus. Some explode vertically, some horizontally, some at an angle. I never got comfortable with which color/number combo did what. These can be dropped a single time by pressing A+B with the CM weapon selected. The bomb will pulsate antidote continuously where it is dropped. Even if you leave a room and come back the CM weapon keeps blasting out antidote where you dropped it.

Puzzle Game?

Each stage has a number of rooms. Each room has a virus that expands in both a random and predictable pattern. Each room has a virus epicenter where the virus is pumped into the room. This epicenter is not always easy to see as the virus spreads so fast and chaotically it is hard to tell from where it is originating. The CM’s are absolutely necessary to defeat certain rooms.

If you drop a CM in the wrong location you might as well die and start over as it will be near impossible to beat the stage. The farther into the game you go the more rooms there are to clear and the more possibilities you have for using the CM in the wrong place.

To my knowledge no one has successfully mapped out a consistent way to beat each stage so there was a lot of trial and error.

The Difficulty Spike is Insane

After hearing horror stories on how hard this game is I was pleasantly surprised by how easy the first level was. It gave me a huge confidence boost.

At the beginning of level 2 I was humbled almost instantly. The virus expanded much more quickly and my gun seemed to do much less damage. I took dozens of attempts before I started making progress. I would say that the difficulty spike between level 1 and 2 is greater than the spike between Level 1-1 and Level 8-1 in Super Mario Bros. 3. It could be the highest difficulty spike I’ve ever experienced in a game.

You won’t believe this, but, level 3 is even harder. You do gain the super gun in the first room of the level, but, if you die you lose the gun making the level near impossible to beat.

How to Die

If you hover on top of the virus you will hear a ticking sound that means your health is being drained. If you hover for too long you will lose a life. This isn’t a big deal as you have 5+ lives with each continue. But, if you are carrying a SG and die you lose the weapon until you get a game over.

Some rooms have a giant hole that opens/closes and spits out a white fire/ghost thing that flies in a straight line until it hits a wall and then ricochets off the wall. It doesn’t move that fast but it does kill you in a single hit and based on how your character floats as if he is in outer space this thing will kill you a lot.

Good news, there are infinite continues so losing a life doesn’t cost you anything but time. If you are brave enough to leave on your NES for weeks you could beat the game and never have to replay older levels. I did this, but, in the 21st century way. I used my Retron 5 to create a save state at the start of each level. So, I was virtually pausing the game. Plus, it gave me the ability to practice a particularly hard room over and over. But, I did eventually get good enough to beat each level with a single continue.

Retron 5 Failed Me!!

After 50+ attempts I finally beat level 3, and right as the game was transitioning from the final room in the level to the cut-scene before level 4, the system froze. I was devastated because of how long it took me to complete. I took a couple of weeks off as I didn’t have the motivation to continue knowing it would take dozens of attempts to replay through that level.

I decided to play on the original NES instead of the Retron-5 to minimize the game freezing. I even took apart the game cart and hardcore cleaned the pins inside to make sure it wasn’t a dirty game causing the errors.

Game Genie to the Rescue

Since the game has infinite continues and I had been attempting to beat the game on and off for 3+ months I decided that I would just use game genie codes to start on level 4 until I beat it and then use a game genie code to start on level 5. This would mitigate any issues with lost power or leaving the NES on for weeks at a time.

But, much like I learned there were no cliff notes for Gone With the Wind the day before the test in high school I learned there are no level select game genie codes for The Mutant Virus.

I emailed my friend Arnpoly from Take on the NES Library to complain about my predicament only to learn that he knows how to create game genie codes from scratch. Less than 48 hours later he emailed me the following codes:


Confidence was restored thanks to these life saving Game Genie codes. Now, I could start on level 4 each night after my daughter went to bed instead of suffering through the first 3 levels again.

Level 4

Pasted Graphic.png

Thanks to the guys on Nintendoage.com for making this handy map.

There are 7 rooms in level 4 and 2 SG’s (super guns). That means if you die with the SG you don’t have to restart the game, you can keep going. But, if you die two times with the SG you might as well start over.

I learned that if you are holding a CM and die you don’t lose it. Also, you cannot hold a CM and a SG at the same time. So my new strategy was to exchange my SG for a CM when my life got low. Then, when I died I could just pick up the SG again after I re-spawned. This is easier said than done but at least it was one way to improve my gameplay.

I had no problem clearing all 7 rooms, the problem was that I could never clear them all in a single attempt. I’d play through once and one room would be a piece of cake and easily beatable in a couple of minutes, but, the next attempt the room would be nearly impossible.

I had a lot of confidence when I had cleared 5 of the 7 rooms and still had both SG’s. I felt that I was finally going to beat the level and then the game froze again. It seems the game itself is glitchy as I couldn’t blame the Retron-5 or a dirty game for the issues.

The next serious attempt I made the game froze again almost in the same spot in the same room. I switched up my strategy and went to the room where the game kept freezing first meaning I wouldn’t lose a half hour of work if it froze again. Eventually the stars aligned and I finally took down level 4.

Stage 5 – The Final Countdown

Pasted Graphic.png

Thanks to the guys on Nintendoage for making this handy map.

I took a short break after level 4 as the holidays were fast approaching. It was probably two weeks after beating level 4 I actually gave level 5 a shot and I died very quickly. I did a bunch of research and watched TheMexicanRunner’s take down of level 5 multiple times and I read through the NintendoAge strategy thread until I had it memorized.

I ended up using GuitarZombie from NintendoAge’s strategy to take down the level. Due to the random nature of the virus outbreaks I had to make some on the fly adjustments but this was the general order:

– Start in room 1, take blue 0.
– Go to room 3, use blue 0 between VSs, clear it.
– Go to room 4, clear it, take green 1
– Go to room 2, use the green 1 on the bottom, clear room. Grab green 0
– Go to room 6 (room 2 to 5, to 7, to 6) use green 0 on Virus Spitter, clear room, Take SG
– Go to room 7 (clear room?), take blue 1
– Go to room 8, use blue 1 on virus spitter, clear room.

I actually took down level 5 in around 10 attempts, much faster than every level except the first one. Even though it took fewer attempts each attempt took at least 30 minutes because the final level featured 8 rooms to clear, the biggest number yet.

The virus in level 8 is ruthless, it kills you very quickly and even when you think your blue wave of antidote is making good progress the virus can take back over very quickly. You don’t seem to earn points as quickly meaning you don’t earn extra lives that often. This is the only level where I consistently got game over because I was out of lives and not because I lost my SG and needed to start over. The thing that makes the last level a nightmare is that every few minutes one of the rooms flashes and you are presented with an audio warning and a message that there has been a virus outbreak. If this happens you have to stop what you are doing and go immediately to that room to get it under control.

The virus outbreaks always seemed to happen when I had a room 90% cleared and was battling the virus for that last 10%. If you leave a room and come back you are pretty much guaranteed that your progress will be erased. On the run that I finally beat the game I would stay put if I was close to clearing a room and hope I made it to the outbreak before it was too late (if you are too late it is instant game over).

The one saving grace in the final level is that there is a SG that you can pick up that never goes away. That means if you die you don’t lose it. The bad part about this is that it is buried deep in the level and I had 3-4 rooms cleared before I was able to pick it up. I technically could have gone to the room holding the SG at the start but then I would lose several minutes of virus clearing time and give more rooms the opportunity to have an outbreak.

I Did It!

I would say The Mutant Virus is 90% luck and 10% strategy. No matter how much you play the game if the computer doesn’t want you to win you aren’t going to win.

I have been playing The Mutant Virus since August, making it’s 5 months completion time the longest of any game I’ve finished so far. Part of that time was me dreading playing the game and not playing for weeks at a time. That is why I beat Baseball in November, I needed a confidence boost and wanted people to know I hadn’t quit the blog.

I would say I did play the game for around 40 hours over that 5 month period. If it hadn’t been for Arnpoly and his game genie code creation I don’t know that I could have beaten this one. Our house lost power 2 times during severe storms since August. If I had chosen to leave the NES on I would have twice had to start over. I know some game playing purists would say that I cheated using the level select code on game genie but I gained no advantage by doing this. I did save a bit of time but I beat each level fair and square and felt the greatest sense of victory I have ever experienced playing an NES game. With this game in the rearview I feel unstoppable. I’m sure I’ll change my mind whenever the next broken, slow, boring, or super hard game appears on the list.

Mutant Virus, The


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