I considered making this a separate thread but still fits in well here......
I truly believe what MS is doing with BC is one of the best things this gen (at least for me). I have both
consoles, but often am buying certain 3rd parties games for the XB1 due to the 360 "free" games being thrown in with it. e.g. Fallout 4, Rainbow Six Siege (though I likely would have bought this on XB1 anyway) and Dark Souls 3 to name a few.
Just Cause 3 is probably the only game I bought for my PS4 instead that had a "free" 360 game attached with it. And frankly, the big reason behind that is that it was on a PSN sale and I wound up getting JC2 for only ~$3 anyway.
In the future, I would be surprised if Halo Wars isn't included with Halo Wars 2.
Looking through my library, I came across these games - that I actually want to play and haven't played before - that I got for "free" one way or another (either bonus games as mentioned earlier, GwG, etc)
Alan Wake +DLC
Borderlands
Saints Row IV
Dark Souls
Dead Space
Fallout 3 - I did start this last gen but never finished
Gears of War 3 and Judgement
Rainbow Six Vegas 1 and 2
Witcher 2
I've been spoiled by this and to be frank would love to see this more.