The corrosive slime carried by the silent Aliens was a bit of a nuisance, so the Players generally tossed them off the train before killing them. B-class Players all had a few long-range attack artifacts. After fighting them and confirming that they weren't especially powerful, and figuring out what their most lethal weapon was, they weren't difficult to deal with.
The large Alien was a bit more troublesome. It looked clumsy, but was actually strong and fast. After nimbly dodging several potentially fatal blows, it leaped off the train with its wounded body and vanished into the darkness.
A few seconds later, its howl rang out in the distance.
The call clearly meant to summon its companions made the Players aboard the train frown. The problem was that there were too many Aliens. If they were also powerful, the Players couldn't kill them all while keeping their distance in the limited space they occupied on the train. If they deployed a large protective barrier, they wouldn't be able to attack through it. But if they each set up a small barrier around themselves, the train might be overturned. On top of that, the train was moving at high speed, so some artifacts were ineffective, and they wouldn't have time to wait for the Aliens to come close.
Some artifacts had a range of more than a hundred meters, but probably because of the peculiar nature of the space around the tracks, they could fail or be drastically weakened beyond a certain distance, making them less effective for defense or killing than expected.
And if the Alien horde grew too large, it might knock the train off the tracks.
"Leave a few Aliens alive!" A Player had trapped two silent Aliens and shouted to the others, "Everyone, move to the carriages