polysquirrel: I will concur however, that much lesser user base means that even initial support may be not viable business-wise, which makes putting extra effort for making even older games work on Linux just far from profitable. Perhaps an extra financial incentive is needed for GOG; a system where we vote with our money for bringing games back. A game might be in store with a huge red flag 'doesn't work on modern systems' and a pledge/vote to bring back button which translates to some financial commitment from the user's part if GOG manages to make it work again. 
  There are over a thousand Linux ports and a thousand and half Mac ports on GOG. Most of which are published by people who have far less resources than anyone who's working on Tomb Raider, for games that are much less popular than Tomb Raider. So that's no excuse. We're first of all paying customers, we're not asking to play games for free. If it's "far from profitable" for developers to support GOG customers the same way they're willing to support Steam customers, then I say that it's "far from profitable" for me to buy their games.   
wolfsite: No chance. The Linux Ports were done by Feral Interactive and they are very Pro DRM .  
 I have played the Linux version of Tomb Raider 2013 and honestly the performance is worse when compared to running the Windows version under WINE or Proton. I did a search and this seems to be an across the board issue with Linux ports from Feral.  
 On top of that it seems the Linux version of TR2013 was pulled by Feral a few years ago.   
https://www.gamingonlinux.com/2022/02/tomb-raiders-linux-port-from-feral-interactive-delisted-on-steam/  
 So they don't seem to care about it. 
  Well, thanks for the informations. I'm not exactly sure what to thing about this. I suppose it could be argued that by not publishing inferior Linux and Mac ports, GOG just did us a favour.  
 But you can imagine, it's not exactly a nice situation to begin with that a game is published as "the best version available on all platforms", then turns out that Steam has Mac and Linux ports that are actually unavailable on GOG, but then turns out that those two were done by a separate studio which is very pro DRM, and then also turns out that those ports may not be so useful anyway.