Grinding for materials in Arknights: Endfield can really eat into your play sessions. The game layers a surprisingly deep factory-sim mode on top of its action-RPG combat, and every upgrade you slap down demands more resources. Some well-chosen promo codes won't auto-build your bases, but they'll kick in a nice supply of currency and materials right when the early game is feeling stingy.
At launch, four codes were making the rounds. Two are already dead, and one of the survivors only works if you're on the PC version—which is a bummer for mobile players. A fresh promo or two have appeared since then, though, so the well isn't dry. Just remember these codes aren't case-sensitive. Spelling, on the other hand, absolutely matters. Miss a character and the game will reject it.
If you've been rerolling for a particular 6-star or you want a better sense of who's actually worth building, our Endfield reroll guide and tier list are probably worth a stop before you spend anything.
Ready to claim something? You need to get through the Process: Cold Start prologue first. You'll know you're there when you have control of your character and you're roaming around the Dijiang. At that point, pause and open Settings—or, later on, hit the small cog icon in the top-left corner of the main console screen.
The rest is straightforward. Flip over to the Platform & Account tab and press the Go button beside Exchange Code. A text box pops up, so type your code in carefully and confirm it. Done.
Rewards don't show up in your inventory instantly, though. They land in the mailbox, and that mailbox isn't unlocked until you push a little further into the story. Keep playing until you clear the next mission, and when the envelope icon shows up, you'll finally be able to grab your goodies.
Before we wrap up: don't bother searching for an online code redemption page, because one doesn't exist. All redemptions happen inside the game. If that changes in the future, I'll make sure this article points you to the right spot.
Above all, don't sit on codes that are currently working. Two of the launch promos have already gone dark, proving nothing lasts forever. Future expiration dates haven't been announced, so if a code works for you right now? Redeem it right now.