Warning!: This is a an Import from Japan, there is little to no English! (And yes the PSP is Region free so it can be played. And prior to playing i would definatly reccomend looking up this games translations for the menu, i found a few of them out there and they really do help.This game is very playable)
Its a Tenchu Title for the PSP in the "Traditional" Tenchu style (Tenchu Stealth Assassins, Tenchu 2: Birth of the Stealth Assassins.)
It plays similar like Tenchu/Tenchu 2, the main thing being you will have to take it slow because of the Draw distance is like it was from the Playstation 1. Draw distance is the "Black fog" you will see when playing this game. Just move slow and you should be good.
The nice thing is this game has 5 characters with their own story as well as a lot of returning characters from the series thus far such as Tatsumaru,Jinnai etc.. I reccomend you read up on the story before hand as the game is in Japanese. You also have the ablitly to play any missions with any of the characters you have unlocked in the "Free/Scenario" mode. i believe they all have their own Stealth kills as well.
And also the Mission Editor from Tenchu 2 returns, and from what i understand it has been updated and is better to work with. ( I dont know know as i have not tried it yet.) You can also upload your mission save files online and let other people who have this game try them out. you can download others missions as well.
This game while certainly not the greatest in terms of graphics etc. it is definatly fun and worth looking into getting this game. And having a "tradiotional" Tenchu game on teh Go is great all in its own.
I would definatly recocomend this game to any Tenchu fans.