Microsoft has said we can expect to see "15 to 20" titles available when Xbox 360 launches in the US next month, although the only titles it's prepared to confirm are the five announced by EA yesterday morning and its three first-party headliners Project Gotham Racing 3, Kameo: Elements of Power and Perfect Dark Zero.

According to director of platform marketing David Reid, the reason Microsoft did not announce a concrete list of launch titles during last night's main address is that they are "currently in the final stages of certification".

Speaking in the boozy aftermath of the main X05 address, Reid told US website GameSpot, "there will be 15 to 20 Xbox 360 titles available on launch day," followed by half a dozen or so more by the end of the year. Along with its first-party titles and EA's launch prospects, others will be confirmed in the coming weeks.

Microsoft's Robbie Bach had previously told the X05 audience to expect the "best games and launch line-up" of any console to date.

Confusion reigned for a short while after the conference when a Microsoft press release headlined "Xbox 360 Launch line-up announced" appeared on a number of US websites verbatim. Closer inspection revealed that just Gotham, Kameo and Perfect Dark were confirmed for the "Christmas portfolio", with the rest of the release given over to details of other games shown at the event.

Those included a brand new exclusive RPG from Bioware called Mass Effect, as well as multiformat titles expected to "lead on Xbox 360" including a new Castle Wolfenstein game from id and Raven Software and Splinter Cell 4 from Ubisoft.

Other titles confirmed for or demonstrated on Xbox 360 at the event included Eidos' Tomb Raider: Legend, a new instalment in THQ's MotoGP biking series, Silicon Knights' Too Human and Real Time Worlds' Crackdown.

Intriguingly, Microsoft also used the X05 address to reveal that Lord of the Rings director Peter Jackson will take a hand in its forthcoming Halo film, acting as executive producer along with his wife Fran Walsh.

Today, the second of X05, consists largely of executive and developer interviews.