The game is very similar to this except it's impossible to do it all in 90 seconds here.
Rules are simple: starting person makes a scenario and starts a sentence with a letter. The next person starts another sentence with the next letter, the person after that does the same and so on. When we eventually reach the starting letter, the person who hit that letter creates a new scenario, picks a new letter, and it starts over.
Example: (starting letter = B, scenario = the office building's on fire) Person 1: "Bring me this month's financial reports." Person 2: "Can't you see the building's on fire?" Person 3: "Does it matter?" Person 4: "Everyone else is evacuating."
Ok now it starts Scenario = You're on the Titanic when it crashes into the iceberg; Starting letter = J
All right, fine. The next topic is: *fanfare* We're all stuck in the bus while we are driving to Farpoo [It's on Jupiter's moon Io], except the busdriver turned into a zombie so someone has to drive while the super mario zombie shoots fireballs at us in bus made of diamonds, and there are zombies crawling over the windshield. You said anything.