Hi everyone!
I have never played any of games from Unreal series and I consider trying out the first game of series.
I have few questions:
- is Unreal Gold on gog.com the version I should be looking for?
- is there some other version that would be easily accesible and would contain sundtrack?
- is multiplayer still played or for that I should check Unreal Tournament?
- is modding allowed by author rights owners and is modding/map making community alive?
Thank you!
Have a beautiful day!

Where to start...

Unreal Tournament (not just 99, but 2004 also) is a classic arena shooter game. Unlike in Quake there is far more strategical options because of the different firing modes of the weapons. The game also very fast at base and there I should tell you something:

-UT99 is more faster than UT2004 when it comes to moving
-UT2004 has more option for special movement that is more faster than UT99's standard moving.

Since the team of GOG takes trouble for patching their games to the latest official release you only have to buy the game here, that's all. If there is missed contents just look at the topics here I'm sure the players links the important files.

Unreal (I'm not sure if just the Tournament series or all other games either) was always one of the most popular title amongst FPS fans. UT99 and UT2004 are the most populated multiplayer FPS games even now. However I have to mention that since the games are old the master server isn't that stabile all the time. The in-game browser show all the public games, but there is a lot servers that isn't listed. If those are worth to play on then it has official clan site or something to say that. You may also free to ask fans here and there about this.

EPIC, the developer of the Unreal Engine was always open for new and original mods as far as they even included award winning mods with the game's re-releases. There is the UDK (Unreal Development Kit) that can be used to build not even mods but games from scratch. You're free to share your projects, and to make it available for download.

There is also an option to licence the engine itself from the author. By doing this you can sell your games that use their engine and generate income.

This is all I got in mind for first. If you still have question do not hold back. :)

Just to add to the excellent post by Pityesz.

There are two types of Unreal games.
1. Unreal 1 and 2 which are really single player games. I think Unreal Gold is extremely enjoyable to play even now. I have never played Unreal 2 so I cannot comment on the quality of the 2nd installment.

2. Unreal Tournaments series, which are arena shooters really focused on the multiplier, but you can also play the maps against the bots offline. There is still community that plays these games online.

The Tournament series and the original games have very different feel. Unreal Gold is kind of slow, there is actually a coherent storyline which is not bad by itself. There are a lot of open areas which in '98 were simply breathtaking though by now they of course lost lots of their initial appeal. But the game still looks good and plays well. To me there is also a huge nostalgic value because I still remember being stunned by the visual which were truly revolutionary at that time.

Now UT99, which was released soon afterwards, is a fast-paced arena shooter, and is the best arena shooter I have played. It is very strategic despite its pace.

Thank you for your responses!

No problem, I hope it helps!