Psyringe: Well ... the characters are ranging from 0-9 or a-f. So I'm pretty sure we're dealing with hexadecimals here. Also, there are 32 of them, and a GOG gift code (we don't know whether it's a GOG code, but it's a possibility) has 16 characters. So it seems that each character of the gift code is encoded by two hex characters in the encrypted message.
However, I can't seem to find the right way to do this ... ;)
IronStar: I think it could be rotated to some degree, and then encoded. It's not rot 13 nor rot 3, those I checked.
Also there is possibility that we got trolled. :D
Well, the message certainly looks like it's encoding
something - it's not an arbitrary mash of characters (since only the hex symbols are used), and the number of characters in total (32) is also suspicious. It might be encoding a joke message of course, we had those in this thread already. But even then I'd like to actually decode it. As I said earlier, I enjoy riddles. :)
Unfortunately, I don't seem to be coming any closer to a solution. I was testing if perhaps the 32 characters in the message can be paired to form hex numbers, which could then be read as ASCII codes. However, if that were the case, then some hex must be much more frequent than others.
The only hex pairs that lead to valid characters (for a GOG gift code) are 0x30 to 0x39 (0-9), 0x41 to 0x5a (A-Z), and 0x61 to 0x7a (a-z). This means that each hex pair must start with a 3, 4, 5, 6, or 7. Of those, it's unlikely for 4/5 and 6/7 to appear both, since gift codes use either only upper-case, or only lower-case letters, not both. Numbers are also less frequent in gift codes than characters. This means that
either 4/5
or 6/7 should be very frequent, and 3 should appear less frequent than those, but more frequent than others.
Even if the character values were rotated in some way, then the frequency of the character should point to a pattern. The most frequent character in the encoded message is _likely_ to represent a 4 or 6, etc. Unfortunately, there isn't really such a pattern among the characters in the encoded message. Many characters appear 2-4 times, no character is more frequent than that. Which means that I'm probably on the wrong track, I just don't know _how_ wrong exactly ... ;)
Edit: Actually, the frequency of the characters _does_ point to a random mix rather than an encoded message. This would be a rather devious joke though, because if it's a joke, then the poster took extra care to make it look like a real code (through choice of characters and length of message).