NOTE: As Necropage33 pointed out in the comments, there is a notorious bug with the gig "Getting Warmer" which I mention below. There is a chance Okada doesn't call you, triggering the start of the gig, and all doors to the building are locked. There's currently no known fix for it. If it happens to you, you won't be able to unlock this achievement, and it potentially impacts Watson too.
Thankfully, unlike "It's Elementary", I faced no issues with unlocking this achievement. Simply complete all NCPD activities and gigs in the Westbrook area. Westbrook surrounds Japantown, North Oak, and Charter Hill. Again, just want to state some things you do and do not have to do, as well as some important things worth mentioning.
First, here is what you do NOT need to do:
- Buy any of the vehicles in the Westbrook area (it is a separate achievement, "Autojock")
- Complete the job "I Can See Clearly Now". This is not a gig, so it should not count towards the achievement. I do believe anything in your Journal under the "Side Jobs" will not count towards this, and the other complete everything achievement(s)
What you DO need to:
- Complete all NCPD Open World activities (can be found in the map, setting the filter to "Open World"). These are the light blue icons, and have labels such as "Assault in Progress", "Reported Crime", etc. Simply go to each one and complete them. My biggest tip to get these done as quickly as possible would be use the mantis blades. I found I could just rush in, chop everyone up and be done in a matter of seconds some times. Reserve stealth for missions/gigs/etc. that require it.
- Complete all Gigs (can be found in the map, set the filter to "Jobs"). Also check the Gigs section in your Journal.
- Occasionally, when you complete one of the 2 above, you get what is essentially a follow-up job. These are simple: go to a location, loot something (and others, but IIRC this was the most common type). You must complete these as well. They are also usually close by to the job/gig you just completed. In my experience, this occurs when you complete an NCPD activity, you might get an additional job (yellow icon) labelled as "Reported Crime". This is where you can gain some extra loot. Again, these must be completed for the achievement.
- Have a Street Cred level of at least 40. I completed everything with a Street Cred level of 43, so you might need to level up a bit. I noticed as I was leveling up between Street Cred level 38-43, new NCPD activities appeared on the map. Apologies I do not have a more specific number, but as you complete things for this achievement you will level up anyways, so it shouldn't be too much of an issue.
- Have started Act 2 in the main storyline (mostly so you can even access this area in the first place). At the time of unlocking this achievement, I had only completed "Playing for Time", and started progressing through the next mission "Ghost Town" to where my current objective is "Meet with Panam".
Now I do want to mention 2 gigs in Westbrook that you should be aware of.
1) The gig called "Family Heirloom". In this gig, you can acquire one of pieces necessary to unlock the "Breathtaking" achievement, where you must "Collect all items that once belonged to Johnny Silverhand". In this job, you can find his shoes. They are in the same locker the bootleg recording/bootleg shard (which is the objective) is in. To get this gig, you must be Street Cred level 37 or higher, and you might have to progress enough in the story where you have talked to Rogue at the Afterlife club during the mission "Ghost Town" in Act 2, as she is the one who calls you to start this gig. I had already done this, so I am not 100% sure if it is required or not. Either way, this gig is located in southeastern Charter Hill.
2) There is a gig called "Getting Warmer". This gig is in Westbrook; however, it DOES NOT have a Westbrook icon in the Journal. You would probably go to this one if you were looking at the map only, but if you noticed it in the Journal, you might have dismissed it. Once I completed this gig, the achievement unlocked (it was the last thing I needed to do).
This one was a lot easier and a lot less time consuming than going for "It's Elementary" (complete everything in Watson). I'll list some steps I mentioned in my "It's Elementary" guide to help you troubleshoot in case you are stuck at 96/98% even at a high level:
- While you do not have to go to the "Fixer" icon at any point, perhaps talking to Wakako could help any remaining missions appear on the map, so it's worth a try
- Really, the best way to see what you need to do (aside from the map) is to go to your Journal and look under "NCPD Scanner Hustles" & "Gigs". Look for any with the Westbrook icon and complete them.
- Go to your Shards (press start, hover over Journal, select Shards). What I did was go through ALL of them, and made sure none of them were labelled as "New". For some gigs/jobs, you do need to read specific shards that you pick up as part of that gig/job, so make sure you do that as well. You can alternate between down on the d-pad and A button to quickly read them all (or take your time and actually read them, if you are interested of course).
- I've seen some people mentioning you should clear your console's cache. I never did this, and I've unlocked the achievement. But it is something to try if you're still stuck.
- Try progressing through the main storyline slowly. It seems progressing through either a part of a mission or completing a mission entirely will unlock further gigs/jobs on the map. But also make sure you have a high enough Street Cred level!