Valve and Microsoft must have worked out a bit of licensing, because both Portal 2 and Left 4 Dead on the Xbox 360 are now backwards compatible on Xbox One.

Looking back on the last generation, Portal 2 is easily one of my favorite games. Granted, I played it on the PC platform, but it joined the PlayStation 3 and Xbox 360 at the same time.

Left 4 Dead was great, too, quite honestly. I know I played through the campaign dozens of times with friends. The same goes for Left 4 Dead 2.

Portal 2  and Left 4 Dead weren’t the only games added to the pile of backwards compatible games on the Xbox One. They join the far lesser known Brain Challenge and Flashback.

Will you be diving into either of these efforts from Valve once more?