I had a brilliant Warhammer Fantasy one once, absolutely brilliant. Me and three mates had just got into the game and were rapidly painting and assembling and picking teams with that enthusiasm you have when you've just stumbled onto something awesome. I reached the scenario section of my rulebook and it was decided we needed to have a campaign as our first real game together. So I started penning an epic.
It took me ages to draw up, each scenario having different outcomes for victory/draw/loss etc so it was like a campaign tree. It wasn't just set battles or a few generic conflicts either, it was a set of story arcs, with different battle conditions and rules based on terrain with actions from previous scenarios having consequences. It was fluffed up with... well fluff and introductory little mission stories, special characters and units, conversions, the whole kit and caboodle.
It began with a 750pt High Elf force ambushing a lightly guarded Dwarf Engineers Guild Caravan (450pts). The Dwarves had to get the caravan off the table edge, the Elves had to disable it or kill all the crew. If the Elves won, they find a map detailing the route of the caravan to a hidden factory of Mad Dog Pass and make a raid with 400pts of troops+100pts for winning and getting first turn, Dwarf win meant the Elves don't find the map, but become suspicious and search the pass anyway, making the same raid without the +100 points and getting second turn.
The raid was played using skirmish rules, and the Elves had to get in and mess up the Secret Advanced Gyrocopter factory with Alchemical Fire in 5 rounds before reinforcements were summoned. High Elf win meant in the next scenario, a pitched battle, the Dwarf players would be unable to use the upgraded Transport 'copter loaded with an elite Dwarf S.Q.U.A.T. insertion team, if the Elves lost, the Dwarf players could use aforementioned S.Q.U.A.T. team. After that battle, the campaign split into different paths and arcs based on wins/losses etc. Suffice to say it was truly epic.
The one problem, my young ambitious and jellylike childish brain severely overestimated me and my mates skill, commitment, understanding and painting speed and ability. Suffice to say... we only every completed the first scenario, and even then one player was using semi-painted Elf spearmen. The campaign was shoved aside for easier, less complex battles, which eventually became irregular before stopping completely. Oddly enough 2 of the 4 of us moved states and never played each other again.
...and so the moral of the story is "don't convert your 8 seater gyrocopters before you paint your crossbowmen w/hand-weapons+sheilds."