This is a deceptively simple challenge. The objective is clear: simply shoot as many falling Whale Oil Tanks as you can during the allotted time.
You will have a pistol with infinite ammo, so ammunition concerns can be waived right now.
This is, in the end, a challenge of pure skill, but there are a few things to know before really digging into the level.
First and foremost, there are multiple types of Whale Oil Tanks that will fall, indicated by their differing colors. Each type will have different passive effects when shot. The purple tanks will explode into a sort of smoke grenade-like cloud of smog when hit, making it harder for you to see the rest of the oncoming projectiles. Pink tanks will resotre a little bit of your health when shot. Golden tanks, on the other hand, will slow down time for two seconds flat, giving you just enough time to line up a tough shot. Green tanks will automatically enable Dark Vision for fifteen seconds, which is great for seeing through the smog caused by the purple tanks.
The challenge will begin with you on a train, and waste no time in launching the aforementioned Tank types in your direction. Simply try to shoot as many out of the sky as you can, and watch out for those you miss exploding when they hit the ground. Remember, a Whale Oil Tank will cause a big bang when it strikes something with a good amount of kinectic energy behind it.
After the first round ends, a Bonus Round will begin in which multiple tanks will fly in your direction at once. Hit as many as you can for bonus points.
This will then lead into a second round, in which two additional trains will appear on the scene and begin launching tanks at you in concert with the first. This is by far the most difficult part of th echallenge. You'll need very quick reaction speeds to ace this one, and you will have to play multiple times in order to wire your brain correctly for shooting down all of the different colors at the appropriate times.
The challenge ends when you die from missing too many tanks.