The rules are simple:

Use one word to start a story and then continue it.

I will start:

Once

commented: it's in the right forum. +3
commented: dont we have too many word games? +0

time

commented: Don't fight amongst yourselves... +19
commented: seriously. +0
commented: then why the heck are you playing them? don't be a hypocrite. -2

dinosaur.

appeared

difficulty