Hmmm.
Weird unmanned ship drifts into a big city harbor straight to the dock.
I'll bypass the issue of how, especially as mention that this game has supernatural elements. But then that makes the investigating personnel frustrated and jumpy if none of this makes sense...
However, regardless of the weather, it seems to me, that this will probably generate a plethora of city and state agencies at work:
- City police cordon until the dock can be surveyed (a large object crashed into it you said). Second cordon/checkpoint at a gangway ramp once established to catch anyone coming off or anyone attempting to get on while the police investigation is in progress.
- City engineering team to survey the dock itself.
- Fire personnel and ambulances (maybe) will show up at least until it is shown that there are no fires nor anyone trapped (in wreckage) that needs to be rescued on land or shipboard. Large port may have specialized fire units trained for ship/water issues.
- A large ship with no authority to land has appeared in a US port. Until it is investigated, again, city police will keep people off of it.
- Customs officials will want to check what is aboard - probably after the ship is cleared as not dangerous.
- City SWAT and/or FBI/Homeland Security (depending on the when of your timeline setting) will check and occupy the ship to see what the ship is, where it came from, where is the crew.
- Once determined to not be an immediate danger, police detectives will board to being to investigate (unless overruled by or teamed with FBI/Homeland security). Probably at least one team will look for the ship's office/captain's cabin for paperwork trying to figure out what the heck happened.
- Blood stains you say? CSI/CSU teams will work on those.
- Harbor police will examine the water around the ship looking for crew; someone may be stuck in a launch to ward off the curious, but if the weather is oh, so poor, a deck watch will probably be used instead). Harbor police/port safety inspectors will probably examine the ship (just crashed into a dock).
- If there is a snowstorm blowing, your snipers will not offer much protection or support due to poor visibility.
- Helicopter hanging out would be rather noticeable to the various agencies aboard and ashore. And they would know how to contact a local official pilot - local agency or news organization - so a loitering chopper would in rather short order become suspicious, especially on a day with a crashed mystery ship.
- Depending on how they get aboard, if you want them to go after ship's papers/manifests, they can ignore most of the ship. These will be in the ship's office or the captain's cabin (where the police and/or FBI detectives will be working). Unless, of course, getting the manifest data is only part 1 of the problem...
Tactical problems
- How to disguise/bluff past multiple cordons to access the ship.
- How to maneuver past other teams to find the manifest/navigation data.
- How to leave the vessel past multiple cordons with as few questions as possible. (I'd use the 'hurt team member' approach, and crowd into the ambulance.
It seems to me more an exercise in stealth and acting than combat, but your mileage may vary.
Personally, I'd go for fire/survey/safety inspectors, with hidden small arms (pistols, SMGs), preferably from an agency unlikely to actually be there "City Health Inspector's office sent us. Yeah, I know the port guys and the Fire Marshall has teams aboard already..."
Have fun.
Uncle Ted