I'm only missing Overseer from the Tex Murphy series. Is this like other GOG gifts codes? if it is, you only redeem the games you don't have and the others are still avaible to redeem for someone else.

If anyone has a spare code that I could use for Tex Murphy Overseer, it would be greatly appreciated . Thank you!

It's an eight character code. I'm not overly familliar with GOG codes, but aren't they normally four groups of characters seperated by hyphens?

Gift codes are the 16 character format. Bonus codes are the 8 character ones, though they are a bit rarer. Not sure if you can only redeem some of the games, but at least you won't have to dig around for the bonus redeem page, since it's currently the same as the gift redeem one.
tl;dr Don't worry, should work fine.

Just got mine and redeemed it for Overseer.

Don't suppose there's been any word on when the Big Finish pack (Three Cards etc) will be made available to backers?