First off I LOVE this game, I don't usually spend $$ on iOS games but this one got me hooked! (Aside from the glitch that hinders play after beating regions in legendary mode) I would give this game/app 10 stars.
Now on to my suggestion, I was thinking it would be cool if there was a live player mode where friends or persons can compete with each other. My idea would be pretty basic, the player does not actually move their character, the players character automatically moves (like the enemy's do during regular play) BUT there would be a new item slot where a player could purchase (or earn through regular play) different types of shoes/boots to make their character more evasive.
Like I said its a pretty simple idea but I'm not a programmer so I'm not sure how difficult it would be to implement such a feature. Anyhow, keep up the great work, I can't wait for the next update so I can get back to blasting thugs.