Getting multiple elements from a list

Hello everyone, i am doing a first year university small project and my goal is to do the “space invaders” classic game in Kotlin.

I am having problems getting all the elements from a list, i’ve done all the work using "last()"function , but i gotta change it. This is all about the spaceship shots killing the aliens, those aliens are on a list, but i can only pick the last one, can someone tell me how to pick every alien form the list? I’ll give u some photos of the work