Hello,
I've bought the Witcher for Windows through GoG a while ago and just saw that it is available on Mac through Steam. Is there a way to get my version to play on Mac or do I need to buy it again.
Thank you

You can run the Windows version of the Witcher on Mac OSX using Wine:
http://www.winehq.org

(Same story as on Linux). Here is an entry in the Wine AppDB, which can give you some hints on how to set up the Witcher to run well under Wine:

http://appdb.winehq.org/objectManager.php?sClass=version&iId=26114

If you'll have some hard time with it - you can ask here.

I think CDProject RED (which i believe owns gog.com?) gives mac version on steam and not gog. So if you originally bought the game on steam, you'll get a mac version, but not if you bought it on gog.com? Also if you buy the game on steam you also get the game on got for free now.

I'm using both mac and pc, so it seems to me that it's an mistake to buy the game on gog.com it it's available on steam?
Gog.com is my favorite digital game provider, but if you always get the better deal on CDProjects own games on steam, there is no reason to stick to gog.com unless you want the old games.

I think it's a bit strange to promote using Steam for CDPR games, when GOG is CDPR's own distribution service. And besides, The Witcher is pretty playable with Wine, so there is no need to buy anything the second time, or to subscribe to the Steam service for that.

Mac OSX version of the Witcher is mostly the same Windows version, using the Wine as a library (see http://www.winehq.org/site/winelib/ ). It has a few fixes in comparison to the regular Windows version of the Witcher (most probably in the Winelib code itself, I'm not sure). But again - there is nothing that prevents Witcher to be playable under regular Wine.

No, W1 for mac is not a winelib app, it's plain wine packaged with wineskin. I'm more eager for W2 tho, since they have announced they will actually make a real port and not a wine based one.

If it's pure Wine, then I'd expect the changes to be available upstream, but they aren't.

As for the Witcher 2, that's indeed exciting, that they are reworking their engine in OpenGL. I hope they'll release it for Linux too eventually.

For those that claim that the GOG.com version of Witcher is playable on Mac using Wine: while this is true, there are serious graphics issues (the famous puppeteer lines among others), which diminish the enjoyment of the game. Furthermore the game will crash very frequently. This is on a one year old iMac 27 with a top configuration.

Even more importantly the game cannot be completed. At the beginning of Chapter 3 the quests given cannot be saved (i.e. if you save and reload the quests are gone). These quests are integral to the story and one cannot progress without being able to play them.

See the discussion in this thread:
http://forum.winehq.org/viewtopic.php?t=12640)

I would hope that eventually the GOG.com version of the Witcher gets updated to resolve these issues. Clearly the game developers must have resolved these issues when they released the game for the Mac on Steam.

Is it Mac Wine specific? On Linux the game can be finished without problems with Wine (besides those visual issues). And looks like that savegames problem affected certain modifications of Wine. They recommend installing Wine through Mac Ports.