The C++ library which you use to make your own games etc. It provides interfaces on how to communicate with the hardware easily. Repository is here.
Program that displays all your games on your SD card neatly, allows you to easily browse them and switch between them. Also has features such as setting the default name and viewing all screenshots of a game. Repository is here.
Little program that always resides in the top of flash. The bootloader is what first runs when you turn your console on. It does some things like initializing some clocks on the board and verifying that a valid program is currently loaded. If no valid program is loaded it automatically tries to load the Loader from the SD card, if that fails it has other fallbacks etc. The bootloader is also invoked when switching between games, it reads binary files and flashes them into the gamebuinos flash memory. Unfortunately no source code available.
Arduino IDE board definition
A simple JSON file which tells the arduino IDE how to use the gamebuino as a board to compile sketches and upload stuffs to it. You can see its json file here. The json file is auto-created using some php scripts based on SQL data, the repo for that is here.
EDIT: And everything has its own version numbering as they are basically independant. The only thing with similar version numbers are bootloader and board definition as they, at least in early development, went a lot hand-in-hand.