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On any attempt to run i got the dialog:
“Blackwell Legacy.app” is damaged and can’t be opened. You should move it to the Trash.
Mac OSX 10.10.1 (14B25).

Verified on 2 machines: MBP 2011 and MBA2013
This question / problem has been solved by triockimage
http://www.gog.com/support/blackwell_bundle/ibread_first_mac_os_xb_faq_and_solutions_for_known_issuesi

Game "is damaged and can't be opened. You should move it to the Trash."
a) Redownload the game using the newest version of the GOG Downloader:
https://secure.gog.com/downloader
To download, make sure the "GOG.com Downloader mode" is switched to ON before clicking the "Game installer" button. After the download is complete, reinstall the game.
b) Use this workaround if using the Download didn't help:
- Go to Applications -> Terminal
- Type in:
xattr -d com.apple.quarantine
but don't press Enter.
- Drag the application to the Terminal window, this should add the path.
- Press Enter.