Syphon Filter Combat Ops is an online multiplayer game for psp, it is available to download from the playstionstore. It's available in the US and also the UK and EU regions.
It cost £6.99 and $10 respectively and once downloaded can be shared with upto 5 psp's or PS3 registered accounts.
About the game If youv'e played Dark Mirror or Logan's Shadow on the psp you will be familiar with the gameplay. It's a third person shooter and uses a really cool game engine. It allows you to host and play online matches with yr friends. Game supports Team Death-Match, Death-Match, Sabotage and Rogue Agent. You can create yr own maps using the map editor or play from official maps and even upload yr own to the server for everyone to enjoy. It supports upto 8 players online. I found it works best with 6 players as you experience some lag when 8 players are matched. Each game you recieve XP to rank up to next level and unlock new avitars. There are the usual weapons found in the Syphon Filter games and you can customise weapons on each map also to suit yr style. Melee maps, Sniper maps, whatever you want goes.
As far as online games for the psp it really is one of the better games for 20-30 mins gaming stints and will have you hooked in no time.
Don't take my word for it read the official review from-pocket gamer
Alot of the bugs that were originally present in the game when it launched have now been sorted and usually there are plenty of people on line to play.
Review stats 8/10
PSP review, Syphon Filter: Combat Ops, Pocket Gamer