Dishonored’s new standalone adventure has quite the setup: you have to murder a god.

Throughout the five year history of this steampunk stealth adventure series, this eponymous deity, the Outsider, has been at the centre of everything – dealing in regicide, revenge and all the juicy stuff in between. He’s an omnipotent force who watches and intervenes from the void – a mysterious place between worlds – giving mortals like Billie Lurk, our new protagonist, spectral powers.

In Dishonored 2, protagonists Corvo Attano and Emily Kaldwin each had their own unique abilities to reflect their personality, gifted by the Outsider himself. This time, Billie has a newly imbued quadruplet of magical skills that suit hers – similar in function to what you’ve played before but with subtle interesting twists. Displace allows Lurk to place a ghostly marker so she can instantly teleport out of danger, or to get to hard-to-reach spots; Semblance allows you to literally steal the face of an unconscious guard or civilian, using it to walk around concealed under a guise for a temporary period; and Foresight freezes time, allowing freeform disembodied perusal of your surroundings to mark guards and targets to keep track of them on your HUD.

Finally, and most amusingly, you can listen to rats. The swarms of rodents offer up interesting titbits of information on the wider world and your current mission in eerie high pitched voices, and it plays directly into Lurk’s backstory as a street urchin. Death of the Outsider also introduces a major gameplay refinement that makes your powers recharge over time, rather than require potions to power up. This removes the frustrating need to scavenge for resources, which detracted from the empowerment in the previous two games.

Death of the Outsider makes the most of Dishonored’s dark and fetid universe. Photograph: PR Company Handout

Lurk’s sudden promotion to leading lady is extremely welcome – she’s always been one of the more intriguing personalities in an already interesting cast, and her journey from life on the grimy streets to being one of the most skilled assassins in the isles is one that deserves a spotlight, even in a story that’s referential rather than original. Death of the Outsider also includes Billie getting back her arm – an appendage she spent Dishonored 2 without – and learning more about the Outsider himself as you find a viable route to killing him.

The five-mission adventure begins with an extraction. The most infamous hired killer of them all, the legendary Daud, has been captured and is being tortured to subdue his incredible void powers. You have to rescue him and, in true Dishonored fashion, it’s very much up to you how you do so. A year since Dishonored 2 launched, it takes this single introductory mission to get back into the mindset of how best to play a game like this – complex options lay everywhere for you to exploit and explore. Even the habit of looking up for multiple routes around each level takes a while to sink back in. Few games offer such systemic freedom, both in their environmental layouts and in terms of open-ended objectives, and it’s best played at a slow pace to soak in the multitude of different avenues of completion.

The next four missions make up a mostly great but inconsistent campaign. The third – a hazy dusklight bank heist – is the clear standout, and one of the most memorable set-pieces in the entire series. Options lay open from the get go, but it’s when you finally crack into the bank itself that things get interesting. You can put staff and guards to sleep while you pursue a particular route of completion, making the mission incredibly tense and exciting thanks to incredible sound design, the presence of clockwork sentinels unaffected by sleeping gas and the ability to wake individuals up if you accidentally nudge them while you’re manoeuvring.

Despite the odd dip elsewhere in the game, there’s largely enough freedom for you to enjoy spending time in developer Arkane’s beautifully detailed worlds, which its environment team revel in, creating grand interiors and dimly lit streets that ooze with an inimitable saturated style. Open hub levels make a return, too, meaning you get moments of respite before a proper mission, in which you can indulge in purchasing goods and upgrades from a nearby black market dealer – or you could break in and steal all the wares for yourself.

Here you can also find the new additional optional contracts. These are essentially extra objectives that lie off the critical path, or parameters for completion for which you can earn extra coin. The bank heist mission challenges you to get in and out with the prize without harming a human being, for example, which at first seems like a standard ghost run, but soon proves challenging when you try to manipulate the bank’s ultra sophisticated Jindosh-designed mobile vault without alerting anyone. To have yet more moving parts in a mission could’ve been overwhelming in practice, but Arkane makes smart use of its objective markers to always allow you to hide things you’re not interested in.

It also avoids overwhelming players by streamlining certain parts of the experience. That means the removal of any meaningful progression of Billie’s powers, which fits a shorter story but does lead to a sense of stagnation by the final level. Perhaps the most questionable omission is the Chaos system. This is essentially a moral compass that, in previous games, follows you depending on the choices you make and changes the outcome of certain events and even transforms entire levels. While its removal makes more sense if you considered Lurk’s already established moral sensibilities, it definitely reduces the player experience.

In the end – and, according to the creators this is definitely the series’ coda – Death of the Outsider successfully sees out one of its most intriguing lead characters and one of its most powerful villains in a worthwhile adventure. Across six or so hours, this standalone indulgence doesn’t add much truly new, instead relying on tweaks of its existing formula . But it delivers strong missions and an excuse to continue skulking around this fabulous and hugely atmospheric world.

Bethesda; PC/PS4 (version tested)/Xbox One; £15; Pegi rating: 18+