"Steam Play: Purchase a Game Once..."

[sklarface]

http://store.steampowered.com/browse/mac
The large banner near the top states
"This week's games feature Steam Play: Purchase a game once and then play it on all Steam supported platforms"

Does this indicate that in the future, [a few? some? all?] games released on multiple platforms will require purchasing OS-specific copies?

I know Portal obviously still shows up as registered to the account on MAC or PC; however, it's also currently being given away free (thus nullifying any insight we might get from its example).

TL;DR: Are we at some point going to need to purchase copies of our games for each OS?

[Crouchin]

You buy the game once and you can play it on any OS so long as you are logged in on Steam.

[Greggers :D]

I doubt Valve would be so cruel.

[vermaak]

The great thing about Steam is that 3rd party developers make games which are sold on steam. The bad thing though is that these 3rd part dev's are under no obligation to give you the windows or mac version free because you bought the other one. It's at their discretion.

Valve though will. which is very nice.

[GadgetDon]

Conceivably some third party suppliers may not allow Steam Play. I'll be honest, I was shocked that we don't have to pay again for the Mac version, so if some third party suppliers don't want to play ball, well, it'll be easy to spot them.

[d10sfan]

From what I remember, Valve wants all their games to be steamplay. Other than that, it is up to certain developers whether or not they want to use steamplay.

[XS-142]

It just states that all the presented titles are SteamPlay. Which only goes to say that some games might not be multi-OS ready.
However from the looks of it the games that are multi-OS will be SteamPlay.

[SnakEyez]

Does anyone know if this SteamPlay feature of having games for both systems goes back to previous purchases made on an account on a Windows system, or is it only purchases moving forward?

[vermaak]

Does anyone know if this SteamPlay feature of having games for both systems goes back to previous purchases made on an account on a Windows system, or is it only purchases moving forward?

Valve did say I think that if you already owned stuff like the orange box then you wouldn't have to buy them again for mac as steamplay will allow you to install it on any system through your steam account be that OSX or Windows.