"Them" is an RPG game with (yet another) good/evil karma system, basically we can be good or evil depending on our actions.
You are playing as a spirit in the world of the living instead of being the usual human victim. You'll start of very weak, dead, floating, and you have no power at all. As you progress further into the story, you will start gaining powers. Starting with the simplest power like, being able to move small object. This is where the good/evil karma system takes place. You can use that power of yours to, either scare people or actually helping them. For example, reminding them of stuff and warn them about something or hide their precious things and scare the hell out of them.
Your power will grow stronger as the story goes. Later we will be able to move bigger objects, throw things to cause harm, or push people out of the way to safety. Around the midgame, you can make yourself visible for a short time. Your appearance will be depending on your good/evil points. The more evil you are, the aura around you will be more menacing and malevolent as well as your appearance. The more good, you are more likely to have more calming aura and harmless presences. You can as well whisper to them.
In the end game you'll be able to make yourself exist in the world and actually doing things with your own hand, this include killing people and helping people too. Well if you don't want to get your hands dirty you can possess people and animals, also this is not excluding good deeds.
Can we die in this game? Well.. You are already dead to begin with, but you can be exorcised and expelled! So there are things that will be in your concern. Such as; Exorcists, Divine objects, those "ghost busters"! and unwelcoming hosts that are equipped to kick you out.