I have both games but only briefly played the first with some GR people and the second at a LAN. Fizzled out after a year or so, great game really. As a HL2 mod it has that feel of not being overly fancy about anything and just throws you straight into the action.
Actually, it's kind of a shame how little recognition it gets now after the wave after wave of zombie horror survival sims that have arrived on all platforms, and that for some reason are still a viable game idea despite being done about 50 times.
We played it every lunch time in the office at my old place for about a month over LAN. I was pretty crap at it, but it was great fun. We also had trackmania LAN games, which I loved. Before I started they were having LAN medal of honour games, and one of the directors had such a paddy he rage quit and went home for the day I beleive the quote was "look will you banana splits just stop shooting me for 5 seconds so I can learn the layout!"
The guy was a total bellend. They ganged up on him on purpose. He had binoculars by his desk (the office looked out over a field) and someone put boot polish on them like in a cartoon. He smeared his glasses, said nothing, grabbed his coat and stormed off and didn't come back in all day.