Earlier today, Sony launched the UMD-less PSP Go and added over 100 downloadable titles to the PlayStation Store. One more title could have been on that list, as a "demo" of Tecmo's Undead Knights included in the early morning update apparently included the full version of the game instead.
The 486MB download has since been pulled from the online storefront, but not before GameSpot was able to get it. The downloaded game gives no indication that it is limited in any way, with full access to all menu options, a working save function, customizable characters, and multiple playable chapters.
Inquiries to Tecmo and Sony about when the actual demo would be made available on the PlayStation Store or when the full version of Undead Knights would join the list of downloadable games (with a price tag attached) were not returned as of press time. For more on the game, check out GameSpot's previous coverage.