Version 1.2-1.5, gosh that's far behind. You are adviced to download the main pack in the Offline Download list starting with the upper part (or re-install the game in GG, it's your choice but I would go with the offline installers, they are more flexible.) That's because the patches from 1.5 - 2.2 are not there anymore, GoG will not provide them for eternity, usually only the 3 last patches are provided, if you want to keep old versions you must download them and save them somewhere, I have them all on a external Hard Disk so I can switch back to older versions if I want, but for main updates (Pathfinder, Altas Rises etc...Synthesis) I download again the main package otherwise I would have to deal with a lot of patches to apply.
Be aware that these patches are NOT cummulative, you must apply each one separately and in the right order without skipping one. If you miss one you can still download the main package again but it will only be the most recent version..

Thanks all. Time to start over! :)

I didn't do all that much exploring the first time, so it won't hurt too bad.

I forgot to say: Backup your savegames before de-installing, you may use them in the future, but I really wouldn't advice doing so, too much has changed in the game.