Left 4 Dead 2's co-op zombie FPS was a massive success when it launched in 2009. Because it was made in the Source engine, fans could easily use the game to create new maps and campaigns to keep the game alive long past its launch window. Some fans have taken that to the max and spent much of the last nine years building something that doesn't seem like it should exist in 2019. However, it does, and Chernobyl: Chapter One looks like a must-play for fans of the Left 4 Dead series.

The story picks up with an infection spreading across the Eurasian landscape. The group of four survivors you play as are on their way to Siberia. Rumors have it that the permafrost of the region will be impossible for the infected to get past. They've chartered a flight to take them there but will need to pass through Chernobyl on the way. You can probably guess that this is where everything goes wrong.

The campaign five maps for you to zombie-slay in and tons of new models that really make the game stand out. This custom campaign is a reminder about how great the Source engine is for creators who aren't as coding savvy. Sure, game development has become more inclusive over the years, but Source gives fans an incredibly easy way to build what they want within some of their favorite games.

Chernobyl: Chapter One and Left 4 Dead 2 are available now on PC. The other chapters will come in time. Fingers crossed it's sooner than nine years.