A high proportion of the original writings on my Poppycock blog are responses to writing exercises that my creative writing group indulged in around the end of the last century. No doubt, if you are a writer you will have come across numerous of these. I particularly like the mini-saga format, as described in the following verse:

Please Count Them
A Mini Saga must have fifty words. Yes, fifty, no more, no less.
So far this effort has scored twenty. Where will I get the rest?
Now I have a dozen more and these make thirty seven.
If I can add but thirteen here, I will reach that writer’s heaven.

In fact, they don't have to be in verse. The only rule is that they must tell a complete tale in exactly fifty words. Some people include the title in the fifty, just to make it more difficult.

Here's another, on a more sombre subject:

Hiroshima August 6th 1945
The condemned pacifist sat on the floor beside the door of his solid stone cell. Suddenly the dark room filled with burning light and a white hot keyhole was branded into the opposite wall. He didn’t know when hearing returned, for sound had ceased. Perhaps he would survive after all.

Go on, pick a subject and try one :)