To cut short , today I've recieved the discount code for PK:imperial editon and I could not resist and proceed to buy it despite I already bought the base version of the game long time ago when it first got published on steam .

This happened because I went back to the game in the last few weeks because I've never finished it , never got past act 2/3.

I was in process of buying the extras on steam , and then GOG gave me everything for a less than the wildcars dlc.

But now I don't know how to "exchange" the version and the save games.

I've connected the steam account to the GOG 2.0 , it recognizes the existence of a copy of the game and some how it registered only one of my steam game achivements, now I don't know if the GOG client will launch the STEAM copy I already own without the DLC or will launch a version with all the content I've bought.

Should I erase the steam copy and re-download a GOG version to unlock evrything? will the save games from steam be compatibile with the GOG one if I manually move them?

It's all clear , I checked and I have both version recognized so I started to download the GOG one, sadly I guess my achivements did not transfer from steam for now.

I'll make a copy for my saved games and see what happens when i'll first launch the game.

Thank you for your answer.