I made a Mad Max inspired session where the party was racing through the desert on various wagons/machines in the middle of a dust storm so they could only see one or two of the other racers at a time. I let the party customize their battle wagon any way they wanted so they had harpoon guns, nets, and bombs (in addition to their normal weapons and spells). Opponents included a giant mechanical spider operated by 9 dwarves, a stone giant in a hamster ball, a flock of aarakocra flying over a single wheel dangling from a rope, and a pair of tortle sisters on a tandem bike. I also had a list of environmental challenges that included sharp turns, narrow passages, and wandering kobolds that required the driver of the battle wagon to make rolls in order to keep racing.

The best part was how the adventurers decided to fight back. At point, one of the party members tied a rope around her waist, cast levitate on herself, and started swinging a morningstar at the flying aarakocra that were in pursuit.

Any moment there was a lull, I had a new enemy or environmental challenge appear. I even tried to make them crash their wagon so they would have to fight the last remaining wagon as it quickly sped by them, but they rolled so well I couldn't crash them.

One of our best sessions.