Ruins/Desert rank system

Yeah I am willing to do that but I don't know what are the players expectations toward this system.
For Arena it was easy because Arena players are competitive - they like to be rewarded for being best not for just sitting in the game - but I have a feeling that Ruins / Desert players are more grinders that prefer to advance and never loose their points. What's your view on that? In other words - should they loose points for dying?

Doesn't matter - do what you want, no matter what, it will be fair for everyone I guess. But personally I think -2 points for death is optimal.

very cool

this may work:

+1 point for kill

-2 or -5 points for death

-5 seems like a lot. I think -2 would work better.

well, death in "wilds" has to be painful

I would not say so, since it's casual. If there would be +2 points for kill, then I'm ok with -5 for death.

Edit: I just noticed how dumb this idea is, because there could be players who kill until they're close to death they could close the tab to avoid penalty. Maybe there should be something like simple points counter? The one that adds all the points you gained. I don't know, it's all messed up when I think about it. Help.

After closing tab/disconnect, your character remains in game controlled by AI (to be honest, really nooby AI :D).

If that's true then I don't see any problems : O

It's casual gameplay, I don't see why you have to make it ultra competitive. If players want ranked fighting, then they can go to the arena.

The problem with non competitive score approach is that after a while TOP 100 is settled and it barely changes over time. You are never going to catch up with grinders that started to play the game X months ago.

So either we make it competitive and add leaderboards for casual mode.
Or we make it like agar.io where you level up no matter how bad you are but then there isn't much sense in adding leaderboards.

Leaderboards should be refreshed every month ;)

This is how it works in other games.

Possibly, but would grinders appreciate having refreshes every month? I just don't see why it has to be done.