[ThrowawayR2]

Since you mention odds, it's interesting to look at the stats of the companies that provide official information about their odds.

For Blizzard's Hearthstone, for example, their stated odds of getting their highest category of cards (legendary) is 1:100 and given that that 1% chance is spread across several different cards across multiple sets, getting a specific legendary card is only a fraction of that 1%.

For Nintendo's Fire Emblem Heroes, the chance of getting their highest category of characters (5 stars), is a relatively generous 6%. However, that's split across 2 batches of 3%, one of which is split across 3 specific characters (i.e. 1% specific card) and the other which has about 100 cards (0.03% to get a specific character). As each character is one who appeared in the long-running Fire Emblem series of games, there's significant incentive to try and get specific characters.

And these are games from companies that behave relatively ethically in this space. I can think of Asian games that are much worse.

[0] https://hearthstone.gamepedia.com/Card_pack_statistics

[1] https://feheroes.gamepedia.com/Summon_Heroes

[minimaxir]

It should be noted that Hearthstone's odds are not stated (in the US): they were only found out by user research, and as a result of Apple's new rule, would likely need to be explicitly disclosed.

In contrast, Fire Emblem Heroes has always been upfront about the odds, and you can see the odds whenever you want. (although in my personal experience the 5 star odds are less than 6%, hmrph)

[ThrowawayR2]

As the link notes, Blizzard complied with Chinese law regarding posting odds and posted a page on their Chinese Hearthstone site (http://hs.blizzard.cn/articles/20/9546) stating that, on average, 1 legendary card could be expected for every 20 packs (of 5 cards).

It is possible that Blizzard uses different odds by region but that seems unlikely.

[minimaxir]

Fair distinction; added edit.

It would not surprise me if odds were indeed different by region. It would be smart to do that, anyways, since player behavior may be different.