Back 4 Blood is on and it's 90% off on Steam right now. Back 4 Blood is (considered) the spiritual successor to Left 4 Dead, although it received mixed reviews. The 4-player coop game did not make a significant impact compared to the Left 4 Dead IP perhaps due to the competing identity crisis attributed to the game that it should be a Left 4 Dead game instead of being Back 4 Blood. However 90% off is a huge discount and B4B is still worth your collection with 90% off.

The largest downer would be that Turtle Rock Studios has announced that they will no longer release more content to Back 4 Blood. But frankly this all suggests a Back 4 Blood 2 to me. I'm also suspicious that Back 4 Blood will soon be free on Epic.

I still feel stupid buying World War Z at full price on Epic only for it to be free after a few days.