In which I have no idea why they did this.

This is a slugfest, and nothing more. Disclaimer: I quit after two waves on the first map.

We’re at the Columbian Archaeological Society. We get a pistol, four vigors and a choice of four areas to fight in: The Ops Zeal (Pier 21), the Duke&Dimwit Theatre, Raven’s Dome and Emporia Arcade.

Several waves on every map, a special challenge per wave (eg. “use only airline strikes”) and the opportunity to restock, change weapons and buy upgrades between waves. Kills earn you money, creative kills probably earn you more money.
Leaderboards are available.

I can see why this might appeal to some. It’s competetive single player shooting, it’s challenging, you can compare your own performance against others.
I don’t like it. I didn’t even finish the first map.
The gunplay in Infinite, lovingly titled shooty times in this series, is solid, but it’s not great.  It certainly isn’t good enough to spent hours and hours blasting away at animated targets.
And it has no connection to the rest of the game. It’s shooty times in front of a Columbian backdrop. We’re at this mysterious Archaeological Society, we travel to places within the city and we shoot at foes encountered before. Why? Because shooting gallery DLC.
The loading screen promises concept art and behind the scenes stuff for playing, but honestly… no. I see what they’re doing here, I’m pretty sure why they did it, but unmotivated additional gunplay in an otherwise story-rich background just for the sake of additional gunplay… no. Not for me.

If you like Clash in the Clouds – fine. You’re probably the target audience for this DLC. I’m not, and that’s okay. I’ll now start playing Burial at Sea.