Here is the link to the Mansion Reports Thread:
https://openxcom.org/forum/index.php/topic,4556.msg62926.html#msg62926I think early on, Black Powder bombs maybe one of the most effective wall breachers.
I personally love the Ripper as a breacher, but Meridian had good success with looted Plasma Pistols he brought along. I think some las pistols might breach with a high enough damage roll. In late game, the Cougar SMG is a dream in Mansions, and I'm pretty sure, I was able to breach with their auto fire to.
Places to breach: The Occult Towers. They only have entrances on one level down low, which one I don't recall. Its often more convenient to breach them on higher levels where your gals are.
Also, I found the top white floor deserved a few breaches as most of these rooms are not connected to each other, but have to be accessed from stairs on the floor below.
Of course, finally, any map generation secluded islands, like you found, nrafield, are the perfect place to breach. Your use of Debug in the case you described, is perfectly justifiable, imo.
The Mansion Mission can definitely be a challenge for the inexperience player, especially where the RNG gods spawn something like this.
That said, Dioxine did provide the alternative, by allowing the player to evacuate from the roof. In your scenario, 200 turns would have been plenty to scour the place and haul any and all loot up to the roof. Not that I'd prefer that method, naturally. I like to kill 'em all too, an haul all the loot out the easy way. And I would feel completely justified to debug kill that last troublesome unit as you did.
