I've owned a PSP for over 3 years now, and only recently decided to clean the dust off it and get this game.
Now you will need the PSP camera for this game to work on your device otherwise you'll just be left with a useless UMD.
Ok the game is basically a AR (augmented reality) game, one of the first I believe on a handheld device, the concept is very simple, you have just been invited (well actually you've bought the right) to join the invizimal world and capture these creatures that can only be seen through the PSP and capture them with the traps you've been give (sound familiar?).
Installing the camera cannot be easier, just slot the connection into the top of the PSP and then tighten the screw lightly (don't tighten too much as you'll risk damaging the camera and PSP), and then you're off.
Gameplay is very simple, you capture a few creatures then compete in competitions, as you win you get EXP and level up , at certain levels your creature will evolve. Very straight forward.
The game is very linear and there isn't really many paths you can take in this game as every thing is about trapping the creatures then fighting, the main storyline isn't very enticing but fans of the old Flash Gordon TV series would like the cut scenes.
I didn't like how you can only catch certain creatures as you progress through the story making it rather impossible to catch some of the more exotic creatures, I know that alot of these type of games are fashioned this was to make you keep playing and hopefully play through to the end of the game, however the variety that you are exposed to are very limited each time you progress to the next checkpoint or chapter.