The controls of a touch screen should be suitable for this kind of game type. Tap on ground and the player moves to the tapped location, tap on enemy player shoots the enemy, long tap on enemy player throws a grenade. The controls must be simple and no new tricks should be added so that the player can focus on the game experience.
I have already created a project to gitorious that includes wiki and the Qt source for the game. I will post more when the project evolves. I just had to spill this out couldn't keep this just my self.
![cool.gif](http://public.gamedev.net/public/style_emoticons/default/cool.gif)
And of course this thread can be used to discuss other vertical scrolling shooters that you have played.
-Mika