I did think of a couple of game ideas - but both have been slightly started on the other MC sites. (1) Author Imposters Tag Wrestling - A story is told by different authors, each trying to guide the story in their style and choice of characters. Stephen King, Enid Blyton and Shakespeare can nuke it out! (2) Animal Diaries - The animals have a game of MC - as told from extracts in their diaries. (3) Or something cryptic.
I was going to remark that the following are currently on my banned list: imposters, combined, bad-tempered, chivalrous, Lord Byron, Bad HTML, ostrich, ham(p)ster and Spartacus.