Wiktionary
minisaga
n. A short saga.
Wikipedia
Minisaga
A minisaga, mini saga or mini-saga is a short piece of writing containing exactly 50 words, plus a title of up to 15 characters. However, the title requirement is not always enforced and sometimes eliminated altogether. Minisagas are alternately known as microstories, ultra-shorts stories, or fifty-word stories.
The idea was originally invented by writer Brian Aldiss and the newspaper The Daily Telegraph, which has held several minisaga competitions, as has BBC Radio 4.