The Showdown Effect is what action movies would look like if they were multiplayer platform fighters. It's a straight up deathmatch, where you're trying to dive, stab or shoot your way to the top of the leaderboard. It has some clever ideas that create very funny moments. Above all, though, it is slick. John Wick slick.
The best way of picturing it is to imagine that scene from John Wick 3 where they crash into a knife emporium (or something) and start chucking knives at each other. You do start with weapons, but it's far more fun to fight with random objects. A pillow might become an impromptu shield, while a mounted medieval axe becomes an impromptu... axe.
Even when you're not chewing up the scenery, fights exude John Wick energy. You can leap at someone when they're at the top of a lift shaft, then ride their body safely to the ground. If you're the character with a jetpack, you can dive into someone as you activate your rocket, and zoom across most of the map. Your victim will get up and and be absolutely fine, but you will look very cool.
Or you would, if you could still buy it. The Steam store page is no more, and the only people who can play are those that already own it. For now, The Showdown Effect is just one more very good, very dead indie multiplayer game. But hope springs eternal!