Ok for example, I start by saying,"Unfortunately there was a giant evil pillow on the the loose; then the next person would say...Fortunately I had a knife with me and stabbed a hole in it"
Ok lets start. Unfortunately I was being chased by an elephant...
Unfortunately, with the humans and aliens, overpopulation destroyed the planet's resources and humans and aliens are now almost extinct, causing them to go to war.
Fortunately, peace ops were successful and they decided to make a strict, authoritarian society which saved the human and alien race. At the expense of terror, they survived!
Fortunately, they conquered that half of the planet, that had simply no resources. It was all the time the plan of dictators of this planet, they let them conquering that part, while strengthening the defense of the other half.
Fortunately, all dinosaurs living on that planet at that time were herbivorous, so humans (or to be more precise the beings that they have became) had no natural enemies.
Fortunately, the humans learnt to tame them and started riding T-rexes and mounting them with lasers and plasma cannons. Yes. Laser shooting army of T-rexes.