Why 5,59 euro? Game is long time free for download (legal, not warez). For example: http://www.edownload.cz/sw/hidden-and-dangerous-deluxe/

I would also like to know the difference to the freeware version.

They are different versions of the game.

H&D Deluxe was updated and in some ways improved, in others the opposite. Deluxe is censored and has clone soldiers, they don't have different faces (SAS or Germans) which makes the game look stupid. It does have a level editor.

H&D1 & Fight for Freedom (the addon) both have different rosters of troops. They combined the games for Deluxe and ignore the addon troops.

They are both worth playing but the original is the one to play through. Deluxe is good for addon missions and modding.

Really? I didn't know that. The censored swastikas are easy to restore, but the thing about the faces is new to me. I'll consider buying the game then. Thank you for the clarification. :)

Thanks for clarifying this. I was wondering why an already free DRM free game was being sold by GOG.

Nobody's forcing you to buy it. The game had over 1,000 votes on the GOG wishlist though.

There is great difference between the deluxe and the original version of the game. But in the original version on gog has been reworked and compatible last windows and hd. The version you paid for 5.39 euro is the original version of the game.

The deluxe version remains free as daggerfall or arena of the series elder scrolls on gog.

But good I advise you to play the original version it is better and more for 5.39 euro and 9.89 euro for hd 2 is not expensive (face the 20 euros of the games activision like timeshift for example)

Small edit
The deluxe version on gog is multilingual (english, french and etc).
The original version may be later.