I recently bought a copy of Civilization III Complete from GOG.com. I've only played with that copy for a short while and so far came across two problems. The first is that the game has some slow down, but that either disappears after a few turns or never appears in a game. The second problem I have is more annoying. Whenever I enter diplomacy, such as when I meet another civilisation for the first time, instead of playing that twinkling sound and the background music, what happens instead is either a quick loud pop or a half second of noise followed by silence. After quitting diplomacy, the in game music returns to normal. I'm playing the game on a Windows 10 computer. So far all I've tried is the compatibility options, I'm not sure if they've made any difference or not but none have fixed that sound problem. I have checked to see if the sound files exist in the game folder and I've played them with a media player.