Subterra

On the outskirts of the Black Mesa
Facility, man-made tunnels connect
various safehouses in which weapons
and supplies are kept.  These houses
have high-security doors and sniper
towers for safety.  The tunnels
are mostly well-lit, but they can be
quite confusing without a map.

After the "incident", two safehouses
were commandeered by scientists and
military personnel, fighting over
the territory between them.  Even
though a firefight in close quarters
is never a good idea, it's the only
option at the moment.