Game Gear -> Master System hacking

People have wanted to play GG games on the big screen for over a decade now. The only solution available out-of-the-box is a "Wide Gear" type system that developers used. It displayed a crisp image from the Game Gear unit onto the television screen. However, this unit is very rare, and probably commands a large sum if one were to sell it. Homemade versions of the Wide Gear work, but they require a moderate amount of soldering work.

Another way to play GG games on a television is to hack them to play on the GG's bigger brother, the Sega Master System. So, with GG ROMs in hand, and a SMS flash cart, let's set about hacking!

Read my Technical Diary about the games that I have hacked so far.

Technically, here is what needs to be done to enable a Game Gear game to run on the SMS:

  1. Intercept the GG game's reading of the GG "Start" button and remap it to a button or combination of buttons on the Master System.
  2. Modify the palette-writing routines so that they write at most 32 bytes (the size of the SMS palette), rather than 64, to the palette RAM. Palette fading, cycling, and other subroutines will also have to be modified.
  3. Remap the GG's 12-bit palette down to the SMS' 6-bit palette. Adjustments will probably have to be made to make it look good.
  4. Insert or reroute code so that the Pause interrupt vector at $0066 will deal with the Pause button on the SMS. Many GG games have code that just barrels past $0066 because this sort of interrupt doesn't happen often on the GG.
  5. Edit out all writes/reads to the GG ports $00-$06. Writing to these ports can crash the system!
  6. ...and undoubtedly something I've forgotten...

As you can see, this is not a task for absolute beginners. It involves a bit of hacking, and a bit of Z-80 programming and trickery. If anybody wants to try out this type of hack, you can see what you have to do. Good luck.

Download the IPS patch for Aleste/Power Strike II (GG->SMS)

Patch v1.00

Please notify me if you notice any errors in the hacked game.

Do NOT send me requests for ROMs or how to use an IPS file to apply patches. Find it out for yourself!!!

GG Aleste II / Power Strike II

Here is one of the best games for the Game Gear! GG Aleste II has great graphics and vivid colours, and the game benefits quite a bit in the transition to the big screen. Your ship can now fly all over the screen, making the game feel less constricted. It's still quite a challenge, though. Enjoy one of Compile's best shooters!

This conversion will correctly display the Japanese title screen (seen below) on Japanese hardware, and the Export title screen (Power Strike II) on non-Japanese hardware. Please note that the game Power Strike II which was released for the Sega Master System is a totally different game from this.

You need to use the pause button on the Master System to start the game and pause in-game.

 Game Gear
Master System
Game Gear
Master System
Frogger goes to Tiannamen Square!

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Download the IPS patch for Pac-Man (GG->SMS)

Patch v0.91

Please notify me if you notice any errors in the hacked game.

Do NOT send me requests for ROMs or how to use an IPS file to apply patches. Find it out for yourself!!!

PAC-MAN

This is a classic game, given a great conversion on the Game Gear. It has both fullscreen and full-size modes, but on the Master System it makes less of a difference since you can almost see the whole playing area in full-size mode.

This game seems to have an ending, but I couldn't reach it (it's still a challenging game!), so I don't know if the graphics will be correct. Please let me know if there are problems during the game.

 Game Gear
Master System
Game Gear
Master System

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Download the IPS patch for The Berlin Wall +4 (GG->SMS)

Patch v1.00

Please notify me if you notice any errors in the hacked game.

Do NOT send me requests for ROMs or how to use an IPS file to apply patches. Find it out for yourself!!!

The Berlin Wall

This action game was converted from the arcade game of the same name, and it plays similarly: you have to dig a hole in the platforms for enemies to fall through. It's a fun and cute game, but it quickly gets frustrating just like the arcade, since the enemy AI in both versions is rather simple and stupid. But I still love this game because of the fun I had playing a great conversion on the Mega Drive called Wani Wani World.

This Game Gear version has puzzle elements added to it. In the game, there are 5 worlds, and on each world somewhere is a door that you must find and enter in order to get the "good" ending. The first two doors are easily accessible, but after that you must "satisfy some condition" in order to make the doors appear. It might have to do with killing enemies a special way, or not dying on a level, or something. I don't know. So until we do know, let's try to solve this intriguing mystery together.

 Game Gear
Master System
Game Gear
Master System

Having trouble with this game?

The enemies can get very annoying. They don't come after you when you want to kill them easily, so you have to chase them, or at least place a trap in their paths.

Here's a strategy for killing off the bosses a little quicker. Unlike with normal enemies, where making them fall through 3 consecutive holes will give you massive points, bosses don't get damaged more if they fall through many holes. They die after 2 falls, that's it. So, the trick is to stagger the holes and lure the bosses up to the upper levels. If you dig a hole (2 spaces for the bosses, of course) in the upper level, dig another hole offset to the side in a lower level. The boss will fall through the top hole, and then hopefully walk off and immediately fall into the next hole... a quick kill!

Oh, alright... if this game is too tough for you, I've added a trainer to it. On the 2nd controller, Left gives you 9 lives, Right gives you the dragon suit for a short time, 1 gives you long-lasting invincibility and 2 skips levels. There. You can thank me via e-mail

(Arcade screenshot)

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Download the IPS patch for Frogger (GG->SMS)

Patch v0.92

Please notify me if you notice any errors in the hacked game.

Do NOT send me requests for ROMs or how to use an IPS file to apply patches. Find it out for yourself!!!

Frogger (Prototype)

A classic! This game got a '90s upgrade with the Game Gear version, but Sega, sadly and unwisely, decided not to release it. It's a shame, as this game is a great upgrade of the original coin-op. The levels are varied; the graphics cute (and sometimes gruesome as you can see below); and the gameplay and control spot-on. Fortunately for us, a prototype of the game surfaced and was dumped for our enjoyment.

I've enhanced the title and ending screens; I hope you like what I've done. The Pause button is used to start the game and pause in-game. In-game, the greater field-of-view is useful, but the top and bottom of the screen still have minor scrolling and graphics glitches, which I can't do anything about for now.

Plus! I have discovered two important secrets to this Frogger prototype:

  1. The dumped ROM is 256k, but the game actually takes up just 128k of this. The 2nd half of the dumped ROM is extra data left over from Streets of Rage/Bare Knuckle. (The ROM code in the SMS/GG header also reflects that it's a 128k game.)
  2. The game has a built-in DEBUG CODE!! At the title screen, press L,2,U,R,L,2,1,1,D,D,U,2,R,D,R,U, and then Start. At the map screen, pressing 1 or 2 selects the starting stage. In-game, pressing 2 turns invincibility on/off! Great stuff!
 Game Gear
Master System
Game Gear
Master System
Frogger goes to Tiannamen Square!

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Download the IPS patch for Pop Breaker (GG->SMS)

Patch v1.1

Please notify me if you notice any errors in the hacked game.

Do NOT send me requests for ROMs or how to use an IPS file to apply patches. Find it out for yourself!!!

Pop Breaker

This is my first successful attempt at converting a GG game to SMS form. It's a fun little puzzle-action game, and the player benefits from the expanded field-of-view in the levels.

 Game Gear
Master System
Game Gear
Master System

 

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