While the first episode hit XBLA in May, later episodes have only been released on PC, where the series concluded in July. Microsoft had dated the second episode for a September 8 XBLA release, only to retract the announcement mere hours later.
The release of the remaining episodes--'The Last Resort,' 'Muzzled!' and 'The Bogey Man'--for 800 Microsoft points ($10) apiece coincides with the twentieth anniversary of the celebrated British clay man and dog's first animated short 'A Grand Day Out.'
A PC demo for the first episode 'Fright of the Bumblebees' is available on FileShack.
I heartily recommend these games. They have a charm that most adventures are missing.