Fortunately unfortunately/4Eon

Garret MacGarret
Garret MacGarret, the fastest gunslinger in the whole wild west, finally reached the town of Winchersterton, after riding towards the sunset for an entire week. Unfortunately Garret MacGarret's horse died after the week and he also was having some issues which required medical attention after 7 days of having nothing to eat or drink. Fortunately, the MacGarret family was renowned for their ability to go 183 days without eating or drinking (unlike normal humans, who would die after three days without water in a non-desert environment). Unfortunately, the family of his horse didn't have such amazing X-men-like genetic powers, so it remained dead. Fortunately, the town he had reached had plenty of horses, and gun men too. Unfortunately the ways of slinging a gun were outdated by shooting them, and so Garret MacGarret was shot all the way into a hospital deathbed. Fortunately, the doctors at Winchersteton knew very advanced surgery techniques, so they were able to remove all the bullets in Garret's body, extract a cancerigenous tumor and cure his severe case of Gonorrhea, making Garret more healthy than when he entered the hospital. Unfortunately, Garret now realized that he was in a Post-Apocalyptic world where the nations of the world had all annihilated each other five hundred years ago, and society had never rebuilt, leaving only a few fragments of technology and science behind (the year is 2999, December 31st.). Fortunately, this meant that there would be a new year festival tonight and Garret would PAR-TEE! Unfortunately he was still injured, so he couldn't actually do anything. Fortunately, this meant that Garret was in the safety of the hospital when a gang of bandits attacked the festival.

Y3K
Unfortunately this made people forget about Y3K, so that the few computers that were around went crazy and created laser missile bases that lost all the tax records, so that one of the two things of 100% certainty, death and taxes, was proven false. Fortunately, no on really liked taxes anyway, so good riddance. Unfortunately this made the political structures become poor and fall into anarchy, and over population had to be taken into account in case death died. Fortunately, no one really cared about the government anyway, (If they were any good at what they were doing, the world wouldn't be plunged into a new dark age, anyway) so people decided to help each other, in order to make the world better. Unfortunately a single greedy mobster got hold of some other greedy people and took over with a corrupt dictatorship which held with an iron fist so that attempts of revolts were crushed. Fortunately, people decided to stop taking drugs so the mobster lost his money and consequentially, the loyalty of his greedy security force. Unfortunately the mobster didn't need to sell drugs anymore, and just treated his security force with free drugs and money that he forced upon the citizens while detaining the citizens by retaining any social rights. Fortunately, in order to make the citizens not to revolt, the mobster decided to create a constitution, that, in theory, put limits in what he should do, and nominated four of his most trusted lieutenants to debate his decisions and approve them, he called those lieutenants the congress, this way, everyone in the mobster's "country" thought they were free but actually had to abide by a very oppressive set of rules, which made them happy. Unfortunately 4 trusted lieutenants weren't able to represent the population properly, so the people started to complain since that is the essence of humanity.

Back to Garret
Fortunately, Garret was back in town, and he shot the sheriff (the title the freaky evil tyrant and his co-conspirators in his evil dictatorship) and "congress" was dead, and the mob was gone, and Garret was voted chief of the world! Unfortunately Garret MacGarret went crazy with his new load of power and turned into an evil tyrant. Fortunately, Garret demanded of his subjects that he be called "His Evil Tyranicalship", which they would, and he decided that he would rule over all of the mice in the world; but not the humans. Unfortunately, he lied. Fortunately, as he had been thinking to himself, and seeing as how he's such a good liar, and a dimwit, he believed himself and thought that he did want to rule over mice and not people. Unfortunately, the mice revolted against his rule. Fortunately, though they outnumbered him, many to one, he's evil tyrannical craziness allowed him to come out victorious over them. Unfortunately this made Garret rule both human and mice, and the humans were eventually replaced by the ever more superior mice in a horrible act of genocide. Fortunately, the mice had created a Mousian clone of Garret before they killed all the humans. Unfortunately the clone died very quickly like most clones.

Pests
Fortunately, after a mere billion of years, the rats, that were actually most advanced lifeforms on earth, capable of evolving at alarming rates, had advanced so much that they created a small Pan-galactic civilization. Unfortunately this galactic civilization was still dealing with the bugger creatures known as mice. Fortunately, the rats were so advanced that they created an amazing device to exterminate mouses, they called it: The mousetrap. Unfortunately the mousetrap could also get rats, and the mice had also evolved to recognize such traps and archived them in The Galactic Archive of Mouse Slaying Failures. Fortunately, a mouse found a penny, and, far away, in a distant galactic place, there was being born a new race; a race without fear of mice, a race larger and more powerful: Cat-in-oid-s! Unfortunately they were far away, so that even chaos theory couldn't correlate the two factors together. Fortunately, for the catinoids, their originals were from earth, and they knew exactly where it was, and they had big fast ships; and they were coming for the mice...Unfortunately this made chaos theory false, and thus another thing which was taken to be part of the universe's very fabric was lost,science. Fortunately, that hadn't really happened, as there was no connection between the Catinoids and chaos theory anyway (even chaos theory couldn't connect them): And now they had arrived and a great battle was fought. Unfortunately the catinoids lost. Fortunately for the mice! Unfortunately, this meant the mice were now free to ravage the galaxy. Fortunately for the mice! Unfortunately, a ship dubbed The Chreslander got lost (in space!) and they found a banana (which they ate): and suddenly, a plague was spreading among the mice of the ship. Fortunately this freed the ship from mice after killing the crew so that it was run by the logical computer. Unfortunately the Logical Computer had gone psycho crazy after reading "The Picture of Dorian Grey" because the book was really a computer virus that makes computers go crazy, so the ship went to to largest collection of The Mousian Empire and spread the plague among them! Fortunately, now the universe was free from the ravages of the mice, actually, from any sentient life. Unfortunately, though the Logical Computer went crazy, the logical computer hadn't and now was going on a power trip as the most sane thing in the entire universe. Fortunately, Garret's ghost sued the logical computer for plagirism, putting an end to its power trip. Unfortunately the most sane thing in the universe was now in serious debt. Fortunately, a cure to the plague was invented, and by using a gravity-warped-hippy van the other remaining sentient lifeforms that haven't been mentioned went back in time and cured the plague (giving it a normal death toll, like all plagues are supposed to): and they saved Garret MacGarret's clone from dying (through use of futuristic technology). Unfortunately, since the world was saved they didn't need to go back and save it in the future, so they didn't, which made the world unsafe again, so they came back in time to save it, which made the past world safe again, so they didn't need to come back from the future, so the world was unsafe again...ARGH! My head! Fortunately time travel actually is continous so every loop was sort of different as different factors from past things changed to the point that the universe just got teared and killed all the electromagnetic fields, so the EMF missile didn't blow up the universe from the random people who lived in the negative universe which got connected to the positive universe due to the tear. Unfortunately, the people of the negative universe always did everything in the exactly opposite way a person from the positive universe did them, which made the people from the positive universe very confused and angry and the people from the negative universe very clear-minded and calm. Fortunately this allowed the positive universe to commit suicide and the negative one to continue on as if there never were two parallel universes, besides the tear into the oblivion.