Vectrex games.
I have all of the commercially available games released for the Vectrex in the US
complete with their boxes, instruction, overlays or colorwheels. I also have the
dustcover, carrying case and fan-club newsletter 'Passport' that were only available
via the Vectrex fan club. In addition to these items (which anyone could have easily
purchased back in the early 80's), I also have the Minestorm 'II' cartridge (which
was obtained by writing a letter to GCE complaining about the level-13 bug in the
built-in Minstorm game in which the game would lock-up after completing the 13th
level. GCE programmers never thought anyone would be able to get that far in the
game so they never really considered it an issue. When customers starting sending
in letters complaining about it, they fixed the code and issued the game in a
cartridge form.) and an original Vectrex Service Manual.
Several games were released overseas with different names, but otherwise the same
games. As far as I know, most of these changes have taken place in the UK.
Web Wars has been released as Web Warp, Spinball is called Flipper Pinball...
Other games have been found that are either promotional or never finished.
Mr. Boston is one of the more infamous of these.
Released as a special promotion for a liquor store chain of the same name, it's just Clean
Sweep with the title screen changed, and the dot eating character looks like a top
hat (Mr. Boston logo). Other discoveries are the test cart used to test various
functions of the machine, Mine Storm II (mentioned above).
Another great discovery is Dark Tower. This game appears to have been completed,
but never released. A prototype cartridge was discovered, and the ROM image dumped
and distributed via the internet so Vectrex fans can enjoy this game. Drawings of
the screen overlay have been found as well, and fans have made full color versions.