The incentives for kindness in an environment where survival is a function of resources and nobody knows each other are… perhaps they aren't non-existent, but we can call them "ephemeral" and retain accuracy. Society is a story we have chosen to believe, because the alternative - while readily observable and undeniably true - is monstrous. And if you would like to see the most ancient human narrative played out in a kind of disemvoweled hyper-efficiency, I urge you to install and play Rust.
You can play DayZ and acquire some of this foundational knowledge, also. Videos which contain this information are readily available. But, again: Rust scours away the basics. It makes you look right at it. Perhaps nine times out of ten, not killing someone is synonymous with killing yourself. With a rock. To the head.
There are some established physical structures in Rust, remnants of some kind, dayzeevian warehouses and whatnot with crates that may or may not include shrapnel of various kinds from a previous civilization. One of the more illuminating experiences was finding a pistol in one of these boxes, and watching the waveforms it gave off careen around the space.
You must understand; after spawning and being pulped or shot through at range or shaken down for medkits and then killed, that nine millimeter pistol was like finding Excalibur. If somebody runs at you from the woods, and they value their time differently from a normal person and will chase you indefinitely, that's it for you. They've essentially taken all the time you spent getting to that point, which we may rightly call Incremental Murder. There should be a legal framework that metes out punishment for this. But if you have a gun - however you came to acquire it - you might as well be fucking Saruman. You don't even need bullets. All you have to do is have the gun out, and wherever you point it, things are altered. Somebody ran at us from the woods with a rock out, and we enunciated our position with supreme clarity vis a vis our pistola. They took off their pants, set them on the ground, and ran away.
Things worked out better for us there, than previously. But still! I did not foresee that outcome.