You understand correctly. It is no longer on my games list. I bought it but never downloaded it, now its gone and I can not longer download it. :'(
As Fuzzyfireball said - contact support, because they didn't remove the game from our accounts.
Maybe your problem is because you never downloaded it, but that's just a guess.
er.. actually I think my problem might be I never bought it. I spent an hour going through my GOG receipts so I could sent it to support, and I can't find it. Now I feel like a bloody idiot.
I hardly ever download games until I'm ready to play them. 90% of the games I have bought on GOG I have bought them because I already own them in some sort of physical format prior. I think of GOG as "Upgrading". I usually then give away the physical media versions. I poured over my bookcase and I can not see Second Sight in there anywhere. There is No way I would have payed that game forward unless I had my GOG version, so now I'm totally confused.
Normally I'd be all "You live you learn" and suck it up, but I'm particularly bummed out here because I LOVED Second Sight. It was close to my GOTY when it came out. Far superior to the very similar, yet "So dudebro its comedy" game "Psy-Ops the Mindgate Conspiracy" that came out around the same time. John is such a great protagonist with real depth, and the way they told the story made you really care about the outcome. Every victory, no matter how small, was just so satisfying. Especially knowing how bad things could have gone if John did not manage to prevent it all!
Anyway, I ramble too much. I've got my XIII downloaded now. Probably play it too. You know, cos its is all so downloaded and everything! :)