Middle-earth: Shadow of War is introducing microtransactions and loot boxes that will let players pay real-earth money for gear that will strengthen the main character. Players are already reacting to the news negatively to the new changes (that aren't story changes.)
Monolith published a blog post debuting the "Market", a digital storefront where Middle-earth players can purchase loot chests, war chests, XP boosts, and "bundles (accessible only with an internet connection)." The post is quite long, suggesting Monolith is trying to get ahead of any negative feedback that's already incoming. And for good reason, considering the backlash paid loot systems have been receiving lately.
The currency system in Middle-earth will be shared between an in-game currency, or Mirian, and Gold, which players can purchase using real money. Monolith hasn't revealed the pricing for Gold yet, but it will be purchasable through PSN, Xbox Store, or Steam Wallet, or otherwise "Awarded in small amounts at specific milestones" or "Awarded for participating in community challenges."
Monolith is also clear that no parts of the game are gated by Gold, and that all content purchasable through real world money can be earned by just playing the game.
Other games currently wrapped up in some form of loot controversy include EA's Star Wars Battlefront 2, which stoked pay-to-win fears when the beta revealed in-game stat bonuses can be purchased through loot. Another loot controversy is currently broiling over at PlayerUnknown's Battlegrounds, though the game's key system is only for exclusive cosmetic bonuses, much like Overwatch.
Still, it's not a good look when you have to repeatedly clarify that paying additional money on your game is completely optional, although as more games try to extend the profits of a single video game title, I fear that loot systems such as the one coming to Shadow of War will only become more common in the future.