Way back before iPhones, there was PocetPC.  Below is the original text and images of it on ClickGamer storefront.  I have compiled it for PC with a larger screen but also have included the original installer and CAB file if you have access to  an original device.

Assaultaire 

Return to your home planet for the fiercest solitary assualt... The Assaultaire.

Battle hordes of enemies over 36 levels. Earn upgrade credits that can boost the power of your guns, the speed of your tank, and your shields. Features a unique control scheme where you use the stylus to aim the turret and shoot - while using direction pad to move and dodge enemy fire.

• Loads of enemies.
• Three gun types.
• Multiple bonus items.
• Upgrade system customizes the abilities of your tank on the fly.
• Smooth rotating overhead graphics.
• Realtime fire and smoke.
• 'Mod' music jukebox system.*

*mod files can be added to the game by placing the in the music directory.

2006 Smartphone & Pocket PC Best Software Awards Finalist!

PC Version:

Controls:   WASD on keyboard + Mouse

NOTE:  the double click to slide means double tapping the A or D.

Registration Code:   none needed

PocketPC Version

Controls:   Stylus + D-pad

This will run as  a limited demo and I need your device name to generate a key for the full version.   Add  a comment  with it and I'll get it to you.