System Prisma, a subsidiary of Nippon Ichi that developed ClaDun: This is an RPG, created a retro style tower defense game for PSP. In Dot Defense you place troops to protect King Pina from monsters. Kill monsters, get money, buy units, rinse, and repeat. Units are a bit more customizable than the typical tower defense game since you can equip them with items and spells.
Following in the footsteps of ClaDun, Dot Defense lets players create maps and background music, but strangely not units.
Dot Defense will be distributed over PlayStation Network on September 22 for 1,200 yen ($14). Post launch downloadable content is in the pipeline. No plans for an overseas release have been announced at this time.