Microsoft has said that the Watchmen game's massive 1.2GB file size was permitted because the company makes exceptions for "superior gameplay" judged case by case.
Xbox Live Arcade games used to be restricted to 50MB, but the company has permitted breaches before, most notably with Castlevania: Symphony of the Night, Bionic Commando Rearmed, Super Street Fighter II Turbo HD Remix and Portal: Still Alive.
"We have set Xbox Live Arcade game file limits as a general guideline. An important part [of] Xbox Live Arcade is easy access, and keeping file size down is a vital part of that," Microsoft explained to Ars Technica.
"Equally important is offering titles with superior gameplay. We weigh both considerations on a case-by-case basis, and will make exceptions when it makes sense to ensure the best customer experience."
Some may scoff at the idea that last week's Watchmen game boasts "superior gameplay" - us very much included - but the breach is hardly surprising given XBLA's competition with PlayStation Network, for which Sony doesn't impose the same size restrictions.
In any case, it's hardly the first time Microsoft has bent the rules, and not just on the subject of XBLA file sizes. Back in the day we were told that boxed Xbox 360 games were permitted to offer 1000 gamerpoints and add 250 in subsequent downloadable content. Halo 3 has since gone on to offer 1750 total.
The last guidance to developers Eurogamer has seen - dated mid 2007 - said that boxed games could offer up to 50 Achievements for 1000 gamerscore, and then up to 10 additional Achievements for 250 gamerscore post-release. XBLA titles were allowed to offer 250 gamerscore off 10 Achievements, and then another 50 gamerscore from a subsequent three.