COD4 for less than 3 euros (WIN/MAC)

Hello guys, there are sales on muve. You can for example buy COD4 for something near 3 euro (2,80-2,85). http://www.muve.cz/digital/hry-pro-mac/call-of-duty-4-modern-warfare-mac-digital/1063 . It is Mac version, but as it is steamplay (http://store.steampowered.com/app/7940/) it also works on Windows when you activate it. I have alredy tried it 2 times, and it works. Those keys may be regionally locked (i am not sure, but it is Czech website) so someone from US or other parts of the world should try. Full list of discounts is here: http://www.muve.cz/promocje/jarohrani. Not every game works with steamplay, so better check it if you want to use Win version on Mac or Mac on Win. For example, BO doesnt :( . 1 Euro is like +- 27 CZK. ENJOY :)