Super Stardust came out all the way back in 2007 and was the first PSN game to have trophy support.  Imagine the simple concept of asteroids except with lot more speed, objects & enemies to avoid, and a whole lot of pretty colors.  If any gave deserved the epiliptic shock warning before you started, this game would be it. 

The game features 5 main planets.  It also offers DLC content for such new game features as Co-Op, Endless, Survival, Bomber & Time Attack.  The game difficulty increases the higher level stages you go and the only thing you want to do is avoid destroying your ship to avoid losing the multiplier.  It will get frustrating trying to go through an entire level without getting destroyed.   One thing this game will also do is it one of the few titles that give 3DTV support.   

I bet a lot of people have played Geometry Wars, but many have not played this game.  I find it even with its age, it is still one of the best PSN games out there.  It has high replay value, and the game encourages you to try to break your previous high scores.  It also gives support for customizeable soundtrack.  Wow a game that support that, amazing!  If only we could get that feature on more full title games.  The DLC packs available to the game only add to the challenge.  It does stay true to its aracde roots and the high score leaderboard will show you how you rank with people actross the globe. 

I highly suggest getting the PSN demo to see if you like it.  If you already own the game, lets compare some high scores in this forum.  I feel this PSN game is overlooked out of the majority of titles available out now.