The rumours are true. Final Fantasy XIII on Xbox 360 isn't anywhere near as impressive as it is on PlayStation 3. The real kicker is that it's a lot worse than it should have been.

Square Enix's latest epic - 4.5 years in the making - follows on the basic principles established by all of its PlayStation predecessors in combining an excellent 3D engine along with vast amounts of pre-rendered CG. This presented two very difficult issues for the developers tasked with porting an already mature PS3 work-in-progress over to the Xbox 360.

Firstly, the Crystal Tools engine needed to be translated across to the Microsoft platform. Secondly, the team had to find a way to compress over 32GB of CG to fit within the confines of three Xbox 360 DVDs - squeezed already by a copy protection mechanism that limits available space to a meagre 6.8GB, less than the storage potential of both PlayStation 2 and Wii.

The sheer idea of porting over a massive Blu-ray game like this onto the Xbox 360 seems like lunacy, but the good news from a conversion perspective is that the game itself is extremely linear. The core basis of the majority of the game is in negotiating very limited environments with just a few branching routes, following a yellow arrow to get to your next destination and fighting a myriad bunch of enemies as you do it.

Very rarely are you asked to return to previous locations - with just one chapter in the game dedicated to the sort of free-roaming JPRG gameplay for which Final Fantasy is renowned.

That being the case, while you can install all three discs to hard drive for a seamless experience, there really is little point over and above the convenience and noise-reduction elements. Disc-swapping on Xbox 360 is kept to an absolute minimum and has next to no impact on the experience of playing Final Fantasy XIII.

Ironically then, one of the main concerns about the conversion proves to be of little consequence at all. Unfortunately, the other niggling worries are of far greater significance.

Xbox 360 owners can install the whole game to hard disk, but the advantages are minimal. The process of swapping discs is fairly unobtrusive.

Built from the ground upwards with an eye towards the storage limitation of the disc, and with the different architectures of the two HD consoles firmly in mind, Square Enix would have stood a good chance of getting the game looking pretty much like-for-like on both platforms. However, by just about every measurable criteria, it seems that the Xbox 360 version of Final Fantasy XIII is a quick port where the existing PS3 material has been very roughly manhandled and bludgeoned into shape in order to work on the Microsoft console.

First up, let's talk about the Crystal Tools engine. Square mentioned in an interview with the Dutch Official PlayStation Magazine that a "new engine" had to be coded up for Xbox 360, but it seems to look and act very much like the PS3 one, with just a couple of very noticeable differences.

Let's talk about the resolution then. A smattering of European and US-based websites have published pre-release Xbox 360 shots, showing a considerable drop in definition with some galleries exhibiting a somewhat washed-out look. The problem with drawing conclusions from media-derived assets is that there's little transparency in what tech they use to take their shots. Some grabs even appeared to have mouse pointers on them, indicating that some sort of PC "print screen" function was used in their making.

However, experienced eyes out there know a legit shot when they see one, and soon the Xbox 360 version was being reported as 1024x576, with 2x multi-sampling anti-aliasing. This is up against native 720p on the original PlayStation 3 version, again with the same 2x level of MSAA, representing a fairly enormous drop of around a third of the overall resolution. So, are the stories about a reduced resolution on FFXIII 360 true? You betcha.

For those curious about how we can be so certain, the principles of pixel-counting are pretty much foolproof. On a 720p game, a diagonal line 20 pixels in height will have 20 distinct steps from top to bottom. When you look at FFXIII, there clearly only 16. So... (16/20) x 720 gives you a vertical resolution of 576 pixels. The same principles - and indeed ratios, in this case - apply to the other axis, giving horizontal resolution of 1024 pixels. The only slight confusion here could come from the HUD, which is rendered at normal 720p resolution before being overlaid on top of the 576p image. This has been standard practice for many years now with sub-HD titles, and FFXIII is no different.

So sub-HD and 1024x576 it is then. Now, with careful handling and superior texture filtering, sub-HD stands a very good chance of competing with native 720p - as Tekken 6 demonstrates. However, Namco's game is pretty much unique in being the only console title running at a lower resolution that looks demonstrably sharper than when it's running at 720p.

Unfortunately, the resolution reduction here seems to be all about converting across the PS3 engine as quickly and easily as possible, and that means accessing as much of the console's power with the lowest amount of aggravation. That being the case, it looks as though Square Enix was keen to maintain the entire framebuffer within the Xbox 360's 10MB eDRAM for optimum processing speed without the need to "tile" multiples of that 10MB into main RAM.

Mirroring PS3 resolution and anti-aliasing would require two tiles, introducing potential performance bottlenecks on elements that occupy both tiles. This isn't really an issue for most cross-platform developers (Fallout 3 and DiRT 2, for example, use three tiles to accommodate superior 4x MSAA), but the only plausible explanation here is that Square Enix had issues getting Crystal Tools working on 360 and down-scaled the framebuffer as a result of that.

So, with a focus on footage generated just by Crystal Tools itself, let's take a look at how the Xbox 360 and PS3 versions of Final Fantasy XIII measure up to one another. Remember to use the full-screen button to get HD resolution, or else use the EGTV link for a larger, more useful window. Alternatively, peruse this colossal comparison gallery of over 50 shots.

"Adequate but a touch disappointing" best sums up the Xbox 360 version. Fine edges lose precision, and while the effect is mitigated thanks to the MSAA along with the multitude of post processing effects the engine has at its disposal, the fact is that the lack of resolution can make the 360 build look sub-par. The clean CG look of the PS3 game in motion is unduly compromised, and while it's still a handsome enough title on Xbox 360, it lacks the pristine presentation of its sibling.

It could have been worse though. As you may have noticed in the movie, the quality of the scaling when watching the game in motion isn't bad at all.