Well you wont come across this to often in the UK, in Europe maybe ten times a year, no other areas have a known release of the Chess Module. I cannot even confirm that this was available in the shops in the UK originally. I know of no significant variants of the chess module other than the PHILIPS long box release, which comes as a cart, attached to a module which in turn attaches to the back of the G7000, The module will work in other machines such as the 7200/7400 types but awkwardly hangs off since there is nowhere to attach the module to. other things to bear in mind for the collector is this is not compatible with O2em, so to play videopac chess ideally you need a G7000 and a actual Chess Module, I'm not sure if this works on the Odyssey2, if you know please mail me to confirm. Although not ranked as super rare, it is hard to find and you will pay a premium for one in a decent box, as there was a insert cut in the lid for display purposes, also you had to take a polystyrene inner out which damaged the thin card outer. much like the Basic module