I beat Rengoku: The Tower of Purgatory. Brief review: There is a lot to be desired concerning the story, shifting the camera can be frustrating (psp issue, no second analog stick), some weapons feel useless and even downright ineffective towards enemies, if you play enough and have an iq above 100 you will realize Bullet based weapons are overpowered (Gattling gun, turrets, smgs, etc), creating combos are almost impossible since weapons don't exactly synergize (the game encourages you to essentially overkill in order to earn upgrades from the robots).

Over all, I will give Rengoku: The Tower of Purgatory a 6/10.
Good portable console game, existential story, and I love robots.