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Assassin's Creed: Evolution of an engine

Digital Foundry analyses Ubi's tech.

Where Scimitar reached its peak in terms of performance as a cross-platform engine was in the 2008 version of Prince of Persia. Developed by the same Ubisoft Montreal studio that brought us Assassin's Creed, it's one of the closest cross-platform releases I've played and suggests that the developers had overcome most of their issues with the PS3, with only the 1080p upscaling proving to be disappointing (thankfully disabled so long as 720p is active in your XMB).

Prince of Persia is probably one of the closest cross-platform projects released, with both platforms showing performance benefits in different areas, suggesting a high level of tuning for both consoles.

Performance profiling shows that the engine optimisations are widespread here. In exact, like-for-like situations we see both machines capable of out-performing the other at certain points while being essentially identical in all other areas. Even then, the only real difference comes down to a few torn frames. While Assassin's Creed remains arguably the more ambitious game visually, Prince of Persia is built on the concept of solid technology powering a beautiful artistic design, with wonderfully realised protagonists. And that's important. From a non-technical perspective, the script and interplay between the Prince and Elika is a particular highlight of the game - let's hope the writing in Assassin's Creed 2 is of a similar high quality.

So, with the past out of the way, what do we know of the future? Assassin's Creed 2 runs on an enhanced version of the Scimitar platform, complete with a new codename: Anvil. Its debut at E3 took the form of a five-minute PS3 play-through. We took a look at the entire presentation here, and in retrospect, while there's nothing in the analysis I'd change, one notable omission having replayed Assassin's Creed concerns the level of detail on faraway scenery: decent in the first game, but clearly improved for the sequel. The initial flybys and the Leonardo glider section showcase this effectively.

It's not just the LOD levels that that distinguish Anvil from Scimitar. It's just that the other improvements aren't quite so obvious in the presentation. Ubisoft, talking to German publication PC Games, revealed that the dynamically generated vegetation found in Far Cry 2 has been incorporated, as has the day/night cycle that worked so well in that game (the time of day also shifts in the E3 presentation). AI has also seen a significant increase - you saw the "seeker" intelligence in the E3 demo, but Ubisoft is also promising that some of your opponents possess enviable parkour skills themselves, which should make the rooftop chases from the first game that much more exciting.

Sections of the E3 Assassin's Creed 2 demo broken out for analysis. V-sync tearing cannot be accurately measured without the source video.

So, that's essentially the performance level of the PS3 game at E3. There's analysis of just under half of the original presentation (compressed video profiling requires a mixture of automated and manual checking and takes a long, long time). Torn frame measurement is effectively impossible on a 30FPS asset, but it's clearly an issue and one that I dearly hope is significantly lessened, even though this would entail a substantial level of optimisation in the short months until the game's release.

That said, this developer clearly has the proven ability to do so, and it will be interesting to see if the optimisation phase of the project sees performance that matches Ubisoft Montreal's impressive work in Prince of Persia, or whether the team is aiming for the same ballpark performance as the original game while incorporating new elements of technology. After all, all the complaining journalists in the world won't cut much mustard up against the stratospheric sales figures of the original game, currently standing at the eight million mark.

From a personal perspective, I'd hope for more, as Assassin's Creed 2 is up there with the new Modern Warfare as one of the most desirable new games of 2009. What gives me hope is that in terms of the quality of its cross-platform development, Ubi has barely put a foot wrong in the last year - Far Cry 2 is probably the only release that has seen a real tangible gameplay advantage on 360, but even that was limited compared to the perceptual gulf of performance evident in the original Assassin's Creed.

Next stop: gamescom. I'll be there, and I hope AC2 will join me...

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