GameBoy was console from Nintando. It was very popular in 90's.
You might be remembering you or your friend having this when you were child.
The popular games for this Console were distributed on ROM Chips.
Now you can play those games on your java phone with this emulator. But this is only for gameboy emulation but not for gameBoy color.
Som of the ROMS I have already installed in this.
If you want extra then there are many websites where you can download the same for free.
Some me these websites where you can get gameboy roms are mentioned below:
Download emulator below:
Some advanced things [Not Necessary]
. How to install new roms:
1. Download correct rom file from some website (or from those mentioned above)
2. Unzip if you get zip file. So you will have some file like xyz.gb.
3. Now using mini commander open cuteBoy jar file in one panel. Browse to games folder.
4. Browse your xyz.gb file in other panel. Then press 5 to copy file inside games folder.
5. Also you will find games.txt file in games folder.Open it by highlighting it and pressing 4.
6. Add new entry in the end as below:
7. That's it. Save the file. Minicommander will do repacking jar file automatically.
8. Install cuteBoy again and play your new rom.
Below uploading source of this emulator. Will be helpful for java programmers and if somebody interested in developing it. The source is distributed under GPL