Looking to get your SP mapping fix? Look no further;
Planet Phillip is hosting a competition for HL2: EP2. The goal is to "[create] an interesting scenario using at least one Hunter. Maps [should] create tension and foreboding of a coming battle."
The competition ends May 3rd. It's meant to be an original single-player mission built specifically for this competition and within the allotted time. Custom content is allowed, but doesn't guarantee better chances. Phillip is the sole judge and if you've ever followed his posts on the site, you'd know he's a fair guy. The cash prize for the winner is $100! Time to fire up the Source SDK and get to work!
You can read all the details
here.