Making a game for Gameboy Color that is also backwards compatible to the DMG is quite a challenge. There are a few small things that Gameboy Color can do that the DMG cannot or that will lag it horribly if you try to do it. When making GbBBS95 I wanted the color experience to be as impressive as possible so I decided I wouldn't leave something out of the color version just so it could work on the DMG. How did I make it work for both with that decision?

First, lets look at what the DMG can't do (besides be in color) that Gb Color does do.

Priority Tiles, you know when you walk behind a tree and the tree covers your character up a little? The Gameboy Color can do this but the DMG does not. In some cases it was ok to just leave it like that, for example in the forest on DMG it looks like you walk across the logs like bridges instead of going through them. I chose the colors carefully so it wont seem like you floated on DMG but still look like deep hollowed out logs on the GB Color.

Tile swapping - tile swapping is a trick to make areas extra animated. You'll see it in GbBBS on the beach, in the sewer and a few other places. The size of the sewer was too bit to have tile swapping, block puzzles and rat enemies on the DMG, it slowed to a painful crawl.

Bigger dialogue boxes - having more than 3 lines of text in a dialogue box is fine on GB color but messes up on DMG.

Lots of moving sprites - The DMG can handle the same amount of sprites as Gameboy color but there is noticeable lag when you have too many.

Changing Palettes - I often change palettes to animate a scene, blinking red alert lights, lightning flashes, etc. When you do this on the DMG it does change the 4 basic colors but its often unpredictable. I also change sprite pallettes to show the character is in the shadow of something or in a shaft of light.

Solving the issues:

Plan ahead :
For the dialogue box issue, I just made myself a rule, only use 3 lines. By planning ahead I never had an issue on DMG and it was fine on color too.

If Color Mode...

Thankfully Gb Studio has a nice If Color Mode Available check. Often times I could just wrap the tile-swapping code or the palette swapping in the If Color Mode check. Sometimes I would use the Else to handle things differently. For example, the red alert flashing in the intro, on DMG is just showing and hiding the overlay instead of swapping colors. It gives you the same feeling without sacrificing something for color.

Different Scenes..

Some of the scenes were just too different to have be full quality on Gameboy color and still functional on Gameboy DMG. For example, the reflections and fog and color tricks used in the sewers on Gameboy Color just made the map look like an insane chess board when you take away the color. The solution? Make a duplicated scene with different tiling. This was a nightmare as the scenes had to be kept in sync if any changes were made. This was also done for the highway  where the telephone poles are in the foreground. There was just no way to make that happen on DMG so the highway scene is a totally different place if you're in color mode or not.

The Testing Challenge

So now we have the following scenarios:

• User has hint mode on or off
• User has fast forward mode on or off
• User Gets the OK ending
• User Gets the Good ending
• User Gets the Secret Ending

So that's 18 scenarios just for Gameboy Color and another 18 for DMG, since some scenes are totally different (sewers and highway) you really have to test and be sure that the game can be completed and everything works properly on both devices and using all these permutations of paths through the game. You can see why we spent over 2 weeks testing!

Anyways, the hope is it will be enjoyable on any device and any way you decide to play.