Smokie? it did worked on my idea but it's a mixes up idea. Between crates and scratch but also from what I've seen in videos with dogCrates, lootcrates, etc.
It's a game very similar to this. They have mystery boxes (or used to) where you could win items, credits and other random items. You had a high % chance of winning common items, mid % chance of winning uncommon items and a low % chance to win rare items.
We have a mystery box on smash , kinda... I can pay Element X and pick between 2 boxes, A box that randomly has a common monster and a box that randomly has rare monsters. It's pretty neat to me so maybe it can be implemented easily here
To actually be lucrative for the devs there need to be options that cause players to potentially lose money as well. Sort of like gambling.
That the whole point of my idea. "Gambling" people will get addicted and will keep spending for that rare drop, but I wasn't supposed to write this so i'll delete it in 4:30