Blood Tracks is a fully supported 3 map campaign for Left 4 Dead 2. It includes coop, versus, survival, and scavenge. Version 2.0 is now released. Changes include level balancing, a new event, improved lighting, more custom assets, bug fixes, and more.
It was fun. I best it within, I think 40 minutes. You really made sure I had a tough time at that final stage. However there was an RV glitching in the first level, but that was the only glitch I found. I had a lot of fun!