Cosmo Tank Prototype Cartridge

Cosmo Tank is a fun little game for the Nintendo GameBoy that was released June 8, 1990 by Atlus corporation. It combines overhead-view tank shooting sections with first-person-view cave/maze-crawling sections. While the game isn't spectacular or anything, it presents a good challenge with decent graphics and music.

A while ago, I came across a prototype/sample version of the game for sale on Yahoo Japan Auctions. Nobody bid on it, so I got it for quite cheap. It was fun to compare the final version and this proto version for differences. Although it is a bit different from the release version, the differences are not major like in the Rockman World prototype. The proto of Cosmo Tank is just missing some music tracks, and lacks an ending. I'll document the rest of the differences below.

Starting off, the title screen of the proto has no music. Also, the title graphic is slightly different -- the two outlines on the final release are white and black, but in the proto they're light grey and dark grey.
No differences here.
Right away, the most obvious difference when you start the game in the proto version is that the select button refills your life, changes between 3 weapons, and gives you 99 bombs! It's a free ride all the way to the end! Or is it...
Another thing you notice if you return to your launching pad is that all the planets are selectable in the proto version.
The main difference you notice while playing is that the prototype's enemy spawning is much simpler -- and much more relentless. Enemies big and small just won't leave you alone!
Inside the caves, you'll notice that the enemies spawn much more often in the prototype version. It's just downright annoying. Graphically, there is a minor difference in the tank's console.


Cave entrance craters are slightly different.
Dialogue in the game is quite different. In some places it's simplified; in others, elaborated on. In the final version she says, "In the room in the opposite direction of the energy core is a shut door." In the proto, she says, "The shut door in the cave will be opened if an energy core is destroyed."
"Beyond the shut door is an item zone"
"There was an item zone just before."
The proto version is missing some supply depots that were added in the final.
Here, you just get advice on where you can get upgrades for your tank.
The graphics in the space shooting stages are slightly different.
Just a bit of spacing is different.
Here, the proto has a supply depot where the final doesn't.


In the spot where you get the hover unit in the final version, you get a girl saying , "I am the warning girl. There's no data here!"
And in the proto where you finally get the hover unit, it is just a life restorer in the final.
The missing depot with the hover unit.
"I'll pray for your success in battle."
No data, and a seriously messed-up face.
There are some differences in the maps in the underground caves between each version. Other places are just bugs in the proto where there appears to be a path, but you can't actually go down it.
One other major difference between the final and proto is that in the final version, when you destroy the main boss in the cave, you automatically exit the cave. In the proto, you have to exit the cave yourself (usually via a newly-opened door opposite the boss' room.) Some exits of this type give you a string of power-ups with each step, only in the proto version.
In the final version, you merely have to go around these boulders; in the proto, they are pits that damage your tank. It's more fun that way, I think.
Text has not been carefully placed in the proto version. It spills out of the window, whereas in the final, the message is displayed over two windows. Also, it looks like the proto has no Katakana fonts, whereas the final does. You can see this in the spelling of "boss" in each window.
Some differences in the planet graphics.
An extra entrance in the proto.
And another map difference.
"The operator with the sensor unit has been captured by the energy core!"
No data.
This is a wide, winding path in the proto, but it has been changed to a narrow path in the final.
This map view shows the differences in the underground maps.
The island has been moved over a bit.
"The monsters are controlled by a Dr. Aihara."
"I'll give you the 5 bombs that I have."
"Please hurry! He is all that stands in our way to shut down 'Greiga.'"
"There, the enemy's big boss is Dr. Aihara."
"He plans to take over the Earth."
"Dr. Aihara is involved with other scientists to take over the Earth."
"Greiga's weak point is the capsule on its head."
"Please take care."
Some small graphical differences (bugs?) in the proto.
"We are descending on the enemy's large fortress!"
"We are descending on the enemy's hover unit." (That's a bug, I'm sure.)
The final base starts to get really weird in the proto version. In the final, you come out of the top of the launch pad. In the proto, you come out of the bottom, and have to pass through the launch pad to come out of the top again.
In the final version, the underground cave's exit leads to the final section of the level. In the proto, the exit leads to a bad pointer. "Hey! There's no warp table here!", a monster yells.
And so we continue to the end of the game in the final version. The ending is pretty short, but it has some nice music, anyway.
The final chamber...
"You've done well to come this far. However, I won't allow you to stand in the way of my ambition!"
"This great powered fortress 'Gidoru' and I will combine our strength. You will realize the great power of the armoured monster head 'Greiga!'"
"I will now carry out revenge against my subordinates!"
"Headquarters! Headquarters! The large fortress is destroyed! I will now make my escape."
With the missing warp table, it seemed impossible to finish the prototype version. So, I did a bit of hacking to see if I could reach the end by other means.
I found a RAM hack that allowed me to pass through any wall. So, it was just a matter of finding the rest of the final level.
After searching through a few "unused" and unreachable areas, it became clear that the rest of the final level was simply not on the map. This portal just leads to...
A cryptic error message. "There is no T#L." Well, there just was no going further. This is the end...

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