Xbox One gamers can get their hands on two more backwards compatible games, this time with Valve titles Left 4 Dead and Portal 2. Both games will be available to play via backwards compatibility starting today.

Left 4 Dead and Portal 2 join the Xbox One backwards compatibility list

Most gamers are probably familiar with the two classic titles from Valve. However, if you've missed out thus far, Left 4 Dead is a first person shooter that pits players against hordes of the undead as you travel through each level. Portal 2, meanwhile, is a puzzle-platforming game through which you use a portal gun to bend the laws of physics to get around.

If you're interested, you can check out the full list of backwards compatible titles.

Update: Three more Xbox 360 games have been added to the Xbox One backwards compatibility list. One is Flashback, the sci-fi platformer from Ubisoft, and another is Microsoft's own Brain Challenge. The final game is Babel Rising, which is not available for download from the Xbox Store.