Grant: Voice Recognition is so bad you'd probably get "Grand Heal" when saying "Fireball of Doom".
I'm for a survival horror game:
Your character and environment is on the bottom screen, on the top is your "PDA". Your character has only one weapon, a handgun loaded with sacred bullets. In order to kill enemies, you cannot randomly fill them with bullets, you have to construct a "seal", that means hitting certain points of the enemy in a certain order. Your PDA will help you with that, showing the seal configs for known enemies and recording your progress discovering them on unknown enemies (a seal point hit out of order is marked in red, seal points hit in order are white and connected with a line showing you the order, the first point is blue). Weaker baddies have maybe 1-4 seal points (before you learn about seals you get told to "aim for the head" because the first enemies have only one seal point that is located there), larger ones much more and end bosses require multiple seals to be performed upon them. Seal combinations are randomly generated when you start a new game. Hitting a spot that is not the next seal point in order will reset your progress in forming the seal, completed seals on bosses stay completed.
To aim, you lock onto an enemy with L and then touch the places you wish to shoot. You cannot move while locked on (or maybe you can but need to keep still to shot, has to be tested ingame). The DPad could be used to select targets or something (alternative selection would be hold L and touch an enemy) if dodging is decided against. Ammunition becomes sparse later on so you have to be rather accurate at forming seals.
Perhaps have enemies later on that have different seal combinations for each instance (meaning that zombie that looks just like the one you just killed has a different seal config) and some kind of psychic aide that you need to protect that can find out the seal configs for you without you wasting any bullets. Perhaps a coop multiplayer mode where a second player gets to play this aide.
EDIT: Oh, and while not locked on you look around by "dragging" on the touchscreen.