Hello,
Let me clear this thing up a bit, yes, there are region locked keys, and possibly keys on Nuuvem will be region locked to Brazil too (my Brazil friend told me so, but he also said that Nuuvem is good and they give region free keys to people not from Brazil), but, my ROME 2 copies are steam gift, bought directly from steam with no region restriction, there is an easy way to check this, you can access ROME 2 Russia store page via this link
http://store.steampowered.com/app/214950/?cc=ru
Now hover your mouse on the Add to cart button, and look at the bottom left, you should see some java ID stuff, here it's 27579, this is ROME 2's AppID on steam store
Now go to the US ROME II's steam store page
http://store.steampowered.com/app/214950/?cc=us
And do the same, you will see the same AppID
Now both have the same AppID, means copies from US or Russia are just the same, with no region restriction, you can compare this with region locked game like Bioshock Infinite, Borderlands 2 .... AppID of these games on RU and US store will be different.