However, publisher Deep Silver was reportedly not sold on the pitch, leading to the project becoming a franchise reboot.
Transporter Skills allow for carrying two bags, negating movement penalties when lifting objects or bodies, throwing bags farther and more.
Cook Off and Turbid Station are receiving some changes to add depth and align them with the sequel's gameplay mechanics.
However, the developer says it's confident that sales will pick up again as the game gets more updates as part of its live service plans.
The company says this is "due to a softer launch where an unforeseen error relating to external matchmaking software impacted the experience for gamers."
Cook Off and Murky Station from Payday 2 are coming to the sequel. There will also be a new Skill Line and over 200 bug fixes.
Is this brief return to HELL-A worth your time?
Last Man Standing and Armor Up will also receive some changes in the next patch, but "big nerfs" aren't planned for other Skills.
Based in Malibu, Haus is a mysterious mansion full of Kult members, zombies, strange biomes and all kinds of twisted things.
Free content updates will also arrive before the year ends, though Starbreeze will reveal more after sorting its patching process.
The patch has been sent for testing and certification to ensure platform parity, but there's still no ETA after multiple delays.
"We have identified some issues that need to be fixed," says Starbreeze, who will provide an ETA on the patch when it's sure of delivery.
First screenshots and details for the expansion revealed, like new weapons and eight Skill Cards, with a new location in Malibu.
The delay is to "ensure its stability" with "some changes that would require us to go through console certification again", per Starbreeze.
With five in-game days and a zombie horde approaching, players reportedly have to earn weapons and set traps to defend themselves.
Starbreeze also outlined its roadmap, with the first patch live in early October with over 200 quality-of-life improvements.
Starbreeze's newest title in the co-op heist shooter series should have been a slam dunk, but falls short in several ways.
Starbreeze can't give a "clear yes or no answer" on an offline mode but is evaluating "every possibility going forward."
Despite matchmaking errors over the period, Starbreeze's co-op heist shooter had nearly 1.4 million unique daily active players.
Starbreeze Studios' eagerly-awaited sequel faces criticism for its crippling matchmaking issues and questionable design choices.
