Isn't GWG just 360 and Xbox One games? Have they been adding Series games to it?
And just curious, but what 360 games would you like to see on there?
Anything that's BC and available for digital purchase should be what Microsoft is negotiating to have on XBL Gold, but the reality is they only choose things these days that cost them a couple bucks at best per game (hence re-using Saints Row 2 because that goes for exactly that during a sale, a couple bucks).
I went flicked through the Backwards Compatible list to see what hasn't been on GWG yet and these are some of the games I found (that I'd want):
Aliens vs Predator, Brothers in Arms 3, Burnout Revenge, Enchanted Arms, Fable 2 (3 was available but I missed that so wouldn't mind a re do lol), Elder Scrolls IV and III, Lost Planet 1/ Colonies Ed, Fallout 3/ New Vegas, Half Life Orange Box, Portal 2, Dead or Alive 4, Mirrors Edge, Silent Hill HD, Blue Dragon, Lost Odyssey, Final Fantasy games, Braid, Call of Juarez games, Command and Conquer games, Condemned, Jet Set Radio HD, The Darkness 1 and 2, Infinite Undiscovery, Last Remnant, Far Cry 1, FEAR 2 and 3, Hitman HD, Metal Gear Solid 2/3 HD, Prince of Persia Forgotten Sands, Rage, RE: Operation Raccoon city, Ridge Racer 6, Shadow Complex, Spec Ops The Line, Timeshift, The remaining Tom Clancy games (Double Agent, Advanced Warfighter 1 etc.), Tomb Raider Anniversary/ Legend, Unreal Tournament 3.
I know some of this stuff is now on Gamepass, but this service has been around for almost a decade now and given that they own a lot of these games outright, they would still add value for Gold members.
Also there's the original Xbox games they've added to BC, which all should be possible to have/ be negotiated to be in Games with Gold too. Additionaly, anything that they knew were being delisted should have been a priority.