Story Mode:
Time line will take place between the original PSU and it's sequel "Ambition of the Illuminus".
You play a Rookie Guardian who will investigate different incidents along with your partner Vivian.
There will be multiple endings depending on the the choices you make.
Multi-player:
Up to 4 players via ad-hoc.
You can use the character that you've made in Story Mode for multi-player.
Characters will speak to each other during battle for players to utilize for better team play, like "Cover Me!" or "Behind Me!".
Overall:
Getting items will be a lot easier compared to the Phantasy Star Universe Series.
The system will be revamped and improved over PSU: Ambition of the Illuminus.
No more random failing when powering up.
Various new fighting systems like "Just Attack" will also be added.
New Items, Weapons, and Bosses are added.
New Fighting/Battle Type(s) also added.
You can import the character that you've created on PSU from BOTH the PS2 or the PC version onto PSP.
Things that can be imported: Name, Race, Gender, Looks, Voice Type, Voice Pitch, Level (Up to lvl. 20), Cloth or Parts Type when you are geared up.
Things you can't import: Gear, Items, Meseta(money), Battle Type, Learned Skills, Items in storage or sharing box, Partner Mercenary.
Phantasy Star Portable goes on sale for PSP in Japan on 7/31 for 5040 yen.
Hit Read Full Story for full scan of the original Famitsu article & pics.
10°
10°
20°
20°
Ad 
10°
