For inspiration for this kind of WoD adventure, I'd go back to classic sci-fi films & stories: War of the Worlds, 5 Million Miles to Earth, Island of Terror, Day of the Triffids, Invasion of the Body Snatchers...even certain episodes of The Outer Limits
A small town, maybe on an island, and these alien (Martian?) or extradimensional spiders are trying to make their beachhead. The invasion begins with some kind of observable phenomenon: perhaps a meteor shower (actually landing pods) or an unusual Aurora Borealis type effect (due to the dimensional portals opening). It starts slowly, but soon builds momentum as they figure out that it is HUMANS that they need to control. (Opportunity to have wild animals or farm animals acting extremely oddly...)
The PCs stumble into the invasion by virtue of attending some festival, either as tourists or for business reasons. Maybe someone in the party is a local. They arrive just in time for the light show.
Any and all locales in the island village can be the battleground, the sewers included. While the sewers might be kind of cool, these are intelligent creatures. They may be more at home running their invasion in the confines of the island's primary power plant. Like pipes? Go hydroelectric or geothermal.
A small town, maybe on an island, and these alien (Martian?) or extradimensional spiders are trying to make their beachhead. The invasion begins with some kind of observable phenomenon: perhaps a meteor shower (actually landing pods) or an unusual Aurora Borealis type effect (due to the dimensional portals opening). It starts slowly, but soon builds momentum as they figure out that it is HUMANS that they need to control. (Opportunity to have wild animals or farm animals acting extremely oddly...)
The PCs stumble into the invasion by virtue of attending some festival, either as tourists or for business reasons. Maybe someone in the party is a local. They arrive just in time for the light show.
Any and all locales in the island village can be the battleground, the sewers included. While the sewers might be kind of cool, these are intelligent creatures. They may be more at home running their invasion in the confines of the island's primary power plant. Like pipes? Go hydroelectric or geothermal.