DS and PSP versions avail for import or at the "store".
DS version uses both screens for bonus stages and has online vs and leaderboards, PSP version gets a different soundtrack and a little more speech (but no online). Other than that no real differences.
It's similar to Pacman CE in that there are chain combos, more weapons, bonuses, etc...it's addictive as hell.
DS version : YouTube - Space Invaders Extreme (JAP) NDS
PSP version : YouTube - Space Invaders Extreme (JAP) PSP
DS version uses both screens for bonus stages and has online vs and leaderboards, PSP version gets a different soundtrack and a little more speech (but no online). Other than that no real differences.
It's similar to Pacman CE in that there are chain combos, more weapons, bonuses, etc...it's addictive as hell.
DS version : YouTube - Space Invaders Extreme (JAP) NDS
PSP version : YouTube - Space Invaders Extreme (JAP) PSP