Saints Row Undercover was going to be a hand-held exclusive on Sony's PSP, until the project was cancelled, but Volition is more than happy to show-off the progress they made.
Originally Volition wanted to just port over Saints Row 2 onto the PSP, but that idea evolved into a full-blown PSP exclusive that could better take advantage of the handheld form-factor and to scale down to the PSP's horsepower level.
Strangely it seems that the majority of the staff at Volition didn't even know it existed until an associate video editor, Josh Stinson, found it by accident while rummaging through a storage room. Thankfully, the senior staff have no problem letting the public know about this would-be project of yesteryear.
Volition had no experience with hand-held games, so they actually contracted out to an unnamed studio to handle it. Progress seemingly went well, though after some internal reviews by THQ and Volition themselves, it didn't quite live up to the standards of the other Saints Row games, so it was canned.
If you want to see more of it, Volition is going to stream Saints Row Undercover on their Twitch channel on January 28th at 4PM EST.