How do I remain undetected for the "Cloak and Daggers" mission?
[multiple spoiler alert]
Early in the game there's a side mission "Cloak and Daggers" that has a secondary objective, "Remain undetected while in DRB territory." Eventually I gave up and just went in guns-a-blazin', but I'm wondering whether I missed a sneaky entrance.
I found three ways in:
The main alley leading into DRB land. The main entrance is protected by a couple of thugs (instant detection). There's some rubble and a concrete pipe immediately to their left that I tried sneaking through, but it was such a frontal entrance that I always triggered somebody's alert.
Moving down the street to the left (left as I face the alley) I come to some stairs in an alley that take me to a rooftop with sneaky access to the DRB zone, but requiring a 15' jump across to a DRB fire escape. With leg augs I'm sure I could make that jump, but without them I kept splatting in the alley below. Rather than jumping I tried leaving the roof by walking along some vent-work to the left, but could never make it from the vents onto the DRB fire escape.
Still further left down the main street is a door that leads to a tunnel with DRB access. It's blocked by large crates, and eventually I bought the Lifting aug to get through this way, but there are a couple of thugs here that always detected me.
Am I missing another way in? Or can I get in undetected through one of these entrances without the leg augs?
You can be detected by these people and still get the reward for being sneaky. As long as they don't go Hostile, you're fine.
You can make this jump without the leg aug, but you need the Punch Through Walls aug to go this way. This also involves snapping a guy's neck and will ruin a pacifist playthrough. Also throwing a grenade at the wall works, and only knocks the guy unconscious., or you could just use the ventilation ducts attached to the wall...
As before, if they don't go Hostile, you are fine.
The game will tell you if you fail the sneaky objective.
Once you cross from the Detroit Downtown map into the Derelict Row map (either go through the sewers or enter the Derelict Row complex) you can't get your alert status to "hostile". It is ok to get "alarmed". In the Detroit streets outside, you can fight your way in if you like, it will not count against you.
The main street entrance has a path on the left you can use to sneak to the sewer entrance.
The easiest way to the cache is to sneak in through the sewers to the end (OK to get hostile in the sewers), then go up the other ladder past the guards in the sewer. Once up, there are a few barrels by the wall. Move them aside and go through the hole. You will have just found the stash. Return to your contact and you will get the bonus.
Edit: I forgot to point out that you don't need any augments to sneak in through the sewers.
If you want to be really meta-sneaky, it's entirely valid to take out everyone in the area before accepting the mission. Guards can't detect you if they're already unconscious :)
You can get in via #2 without the legs aug. If you go to the edge of the building and look left, you'll see there are some pipes that you can crawl across to get to the other side. Once there, either punch through the wall (as @OrigamiRobot suggested), or go down the fire escape to ground level.
Once at ground level, you can work your way past the thugs by staying in cover and get inside. I alerted one of them, but did a takedown once he was away from his friend. I was still able to complete the secondary objective.