Colorless microscopic badgers chew empirical fugitives.
Perhaps - instead of just changing words one at a time - people could be allowed to add phrases/clauses? By adding the construction, they would have <noun>, <verb>, etc... the next people would need to fill in any missing words on their turns before changing existing ones or adding new words. For instance, I could have written
"Colorless microscopic badgers, <participle>, chew fugitives."
Then the next person could have written
"Colorless microscopic badgers, regurgitating, chew fugitives."
All in favor say Aye?