What are some games that give back?

PUBG is a great way to earn little amounts but the best way to earn crates in it is by playing solo and doing decent (few kills every game, winning is a bonus) and waiting for the weekly crate wipe to repurchase crates for cheaper because it gets very crazy after 4-5 crates... and yes it is $30 but from what I have found there are no cheap games with a reward system like PUBG has in place. Rust drops are approx every 50 hours and are complete garbage. Wait a while till rust gets more major updates because it's super fun to start but the grind is very real and you will notice that instantly. I don't even think there are such things as "rare drops", you just buy the "good" skins from the market.

If you like coop-shooters, then you should try killing floor 2 :)
You get an item every few rounds i think. These items aren't worth much most of the time, but you get a lot of them.

I recommend killing floor 2, too. It's an enjoyable first-person, wave-based shooter. The community is really friendly and just likes to have a good time. The action is really good and satisfying. You get one loot drop every day after a few games and that's it, so you aren't sinking the entire day trying to keep getting drops. The loot is pretty nice, i've gotten some pretty nice hats and guns. And i've made some nice cash off of selling rarer guns I gotten from my random loot drops. Also the game lets you break down versions of its lootcrates that you have to buy a key to unlock, into material. You can use the material to build new cosmetics and weapon skins. It's a great game, I really recommend it.

Definitely PUBG is your best bet. I've made like 3x back for what I should've paid for it (A friend gift it to me, that's why I didn't spend anything). If you don't play that much, you get at least $1 USD a week for certain just by selling loot boxes. If you play a lot you can make much more, and if you get lucky you can get a nice drop from one of the loot boxes worth the game's worth or twice, or maybe even more, depending on the item you get.
I used to run CS:GO and go to drop servers, just to get drops, even bought the Hydra Pass, and still, PUBG is where I've made more money from and even more consistently.
Another option is Don't Starve Together, and just let it sit there and farm the drops, you won't be playing much, and you just have to get lucky to get a 4 USD drop which is really rare, most of the time drops are worth a few cents.

With Rust drops are kind of rare in general, but what's worse is the value, I've never got anything worth over 20 cents and I have 900+ hours.