
Assassin's Creed Shadows is a major tech demo for Ubisoft. It leverages a powerful Anvil engine to build a deep world in Feudal Japan. The game will drop on March 20, 2025, following a delay from its initial launch in November 2024. It will try to push the boundaries of new gaming hardware beyond what the PS4 and Xbox One can handle.
This piece takes a close look at the technical underpinnings of Shadows, and how Ubisoft employs its approach to set a new standard for visuals, physics, and immersion in this stealth thriller.
The Anvil engine, a mainstay of Ubisoft since Assassin's Creed in 2007, was overhauled in Shadows. Originally code-named Scimitar, this engine has powered every mainline title, adapting to the needs of each era. For Shadows, teams rewrote Anvil to leverage PS5, Xbox Series X/S, and PC hardware alone. The key improvements are ray-traced global illumination (RTGI), replacing baked lighting employed in previous games such as Unity.
The adjustment enables light to dynamically interact in Japan's environments, ranging from misty forests to sun-kissed villages. Micropolygon geometry systems, such as Unreal Engine's Nanite, eliminate level-of-detail transitions so terrain may be displayed smoothly. These technologies break with cross-gen compromises to visual quality at the expense of backward compatibility.
One of the standouts of Shadows is its physics-based world. The Anvil engine brings with it the Atmos system, which simulates weather through fluid dynamics. Clouds naturally form and disappear, and wind blows on leaves, hair strands, and even water. Destructible environments play another note: swords cut through bamboo, and icicles break to disorient enemies.
To keep this complexity from going awry, developers streamlined CPU use by combining numerous objects into a single instance during build creation. The process, explained by Technical Director Pierre Fortin, scales thousands of objects for interaction without slowing down. Seasonal changes further enrich the world, changing vegetation and terrain, snow slows movement, while summer bushes provide shelter, marrying aesthetics with gameplay use.
Rendering in Shadows finds a middle ground between ambition and pragmatism. RTGI, being revolutionary, comes at a high computational cost. To maintain 60 FPS on consoles, Ubisoft found a balance, providing particular areas with real-time ray tracing like the customizable Hideout, while open areas utilize enhanced baked lighting. The compromise maintains frame rates without compromising much visual nuance.
On PC, three modes of ray tracing: Selective, Full, and Software-based, allow heterogeneous hardware, making it accessible. The choice of not including AMD's FSR and opting for proprietary Temporal Anti-Aliasing (TAA) is a resource allocation towards higher pre-upscale resolution, though support for PS5 Pro's PSSR was added later. Virtualized geometry adds density to detail, decreasing pop-in, but foliage transitions are still apparent, implying system limits.
Technical innovation within Shadows manifests directly as mechanics. Stealth is affected by dynamic weather: rain dulls sound from footsteps, fog blurs lines of sight, and wind reorders enemy patrols. Seasonal change determines strategy, with winter revealing hiding places and spring providing new routes. Advanced NPC AI, fueled by Anvil's enhancements, responds to environmental stimuli, such as examining broken icicles.
Crowd simulations, another series staple, are taken to new extremes, with GPU-rendered simulation churning out dense settlements with ease. This fusion of tech and design is designed to increase immersion, making Feudal Japan a living, interactive playground for heroes Naoe and Yasuke.
Expanding Anvil's capabilities was not without issues. Early demos revealed light leaks and flat shadows, hinting at a probe-based RTGI system rather than per-pixel precision. November 2024 to March 2025 delays added fine-tuning and refining over fan criticism of early gameplay trailers.
Optimization work went into GPU utilization: micro polygons and physics depend greatly on graphics hardware, eliminating CPU load. Older GPU support via software ray tracing demonstrates a commitment to broad PC compatibility, though Steam Deck falls short of minimum specs. Cross-save and Steam integration further ease accessibility, eliminating Ubisoft's launcher for simpler player entry.
Shadows sets a technical bar for Assassin's Creed. Casting off last-gen hardware enabled developers to tinker with next-gen possibilities, a development bound to impact games such as Codename Red. The 17-year development of the Anvil engine illustrates its flexibility, on par with engines such as Snowdrop utilized in Star Wars Outlaws.
Far from flawless, with minor visual quirks still present, Shadows attests to Ubisoft's dedication to merging bleeding-edge technology with the series' stealth legacy. This technological foundation is a bold step forward, with richer worlds and wiser systems coming for the franchise's ongoing saga.