8% for the majority of it at these numbers, rather than 18. And do we know how Epic retail keys are charged? Possibly 12% loss on those vs 0% for Steam? I have no idea.
There's the fees for Unreal Engine too, but again no idea how it works at this level - I don't think these big AAAs deal with the 5% anyhow?
You only get 8% once you cross a threshold of sales, which I don't think Valve applies that retroactively. Epic is just flat. Plus they waive or reduce some Engine fees for using their store. It is cool that Valve lets you take more revenue, but earning that privilege is exclusionary. Borderlands wouldn't have that much trouble reaching it, but who knows what the timetable and payout methodology is. Meanwhile, that is all money you aren't pocketing to recoup costs or reinvest.
As for the keys... I don't know. I was sure Epic just borrowed Valve's approach.
Ultimately, I think a lot of folk in this thread are trying to downplay how smart of a move this was for 2K/Gearbox. Free upfront money, waived engine fees, a higher cut of every sale from the get-go, top billing for weeks on a growing store. Plus, the game is only exclusive for a 6 month period. It will come to Steam later with updates and more content, likely on sale. It will get a second-wind.
I have little doubt Gearbox, 2K, Epic and eventually Valve will be jubilant.