You posted that after the deed was already done.

(( I think I'll eat the loss and not risk my Steam account. Like Drabe said, I already revealed the key.
Well I've mentioned it multiple times before that, but one more time for good measure:
DON'T BUY SEGA OR DEEP SILVER GAMES FROM OTHER REGIONS
disclaimer for anal nitpickers: yes I know sometimes the DLC might still work.
There's a few pubs too known to region lock like Bamco and sometimes Capcom, but Sega and Deep Silver are hardcore and almost always region lock to Russia and even Brazil lock as well.
If you're not sure check the Steam database for RU/CIS/BR/SA entries, scour Reddit game deals for current or past deals on that game (people there will always mention if something is or isn't region locked) or just ask.
Also with Gamersgate check the urls. If you see an "RU" in it then don't buy it.
If you do get stuck with a region locked key, as I mentioned before you can activate it with a vpn on Steam in most cases (a real one; not a web browser one) but there may be some risk and it's not something you want to do on a regular basis to avoid getting your account flag. Edit: Listen to Syntax Error on this. It's been a while since I VPN activated that Valkyria Chronicles key from GG and they may have changed that process by now so best not to risk it.
Trading with a Russian is probably the safest option at this point.
Thing is, I was kind of hesitant to start talking about this here in the general thread outside of the private chats because I knew sooner or later someone would do this and be like 'OMG you guys didn't tell me'.
Those of us who do this sort of thing generally check into it first or hear from someone else that did. If you don't see one of us talking about getting that particular game here then check first or ask.
And whoever the bozos are who are posting here about Russian sale pricing on Sega games (was it Tomasety?) Please stop.
TL;DR - Putin'in at Gamersgate. Kids, don't try this at home.