So I bought the Sword of the Stars from the sale here on GOG. I downloaded and instaled the base game, ran it to make sure it worked. than attempted to install the Gold Edition Upgrade but it tells me that the base game is missing... even though It's installed and I was playing it...

I'm not sure what to do...

Install Mindgames DLC and then Gold DLC.

Yeah I just discovered that. What is in the Gold Edition anyways?

3 playable alien characters (+ one hidden) and a LOT of monsters, items and ingredients.
Pilgrim DLC takes it further :)
And also we are still waiting for Juggernaut DLC which was released two weeks ago on Steam.

This game has a lot of content and it's super hard :)
I once died on level 0, yeah I didn't even make it to the Pit and was slain by a group of bats :)

So the Gold Edition adds all that on top of whatever the Mindgames DLC added? Sweet. I take it Gold Edition won't give us Juggernaut when it's released on GOG

I suppose not, it should be the same as with Pilgrim DLC which is a separate purchase.

What's the Pilgrim DLC give ya?

Well, as usual: additional playable character (Zuul - very fast and very hungry :), new items, monsters, recipes, etc.

Juggernaut seems like a lot bigger change because it comes with new recipes to change ammo types and modify standard weapons to be more efficient.
It also comes with a big nerf to psi costs and regen times so if you are a new player then you should stick with Gold for a while.

Seeker, which is heavily based on psi abilities seems like easiest character overall.
But most fun for me was the Scout.

Same issue here- but if we need the Mind-games DLC, why was not that stated in the "you need these to run this" section? I just got the game and the gold upgrade along with the necromancer dlc without knowing that i ALSO NEED the pilgrim....GOG needs to update their required games/dlc list for this game....too confusing!!

I think the best way to install without melting your brain is to go by version number.

Download all the parts you own and start with the lowest number and end with the highest :)