Tesla Toy 4+

I'm hooked already. It's just one of those relaxing, fun, don't have to think, type of APPs.
It goes from looking like a universe to whatever you can imagine.
I'm enjoying it.

@ Coolridr : you can get this app without having to pay for it. All you have to do is go to your settings and scroll sown until u see the store symbol, click on it and sign out of your account then sign back in under your wife's account. After u do that go to the app store and click on it to buy it, when it starts loading it a window will pop up saying "you have already purchased this app, would u like to download it again for free?" and you click on yes. And there ya go you got the app for free. Just remember when it's done downloading to sign out of your wife's account and back into yours. An apple rep told me how to do this, actually several told me how lol. Good luck and happy downloading. 

You could add a settings page
To controll options and attitude of your app to alow a more in depth experience and keep costomers involved and interested with this app.

Settings page could have....

Select the collor or collors of particles

tilt gravity options (on off)were u tilt it and all particles flow were u tilt it.

Maby you could add a slider controlling the life span if the particles were they dont just go away after a second, you could have them live n bounce around a while or somthing making cool designs.

Aswell as the distance or radious the particles fly And how violent they fly off or just speed.

Maby chose how they fly off,
so smooth arcs will look more like fireworks
Or zig zag particle trails so it looks like electricity shooting out your fingers and patterns.

An option were u could draw a line and the particles would constantly flow from ur drawing in a cool way.

So u could have a epic sparkly smily face or whatever my kid draws.
And with gravity tilt on u could make the sparkly smily grow a beard and cry or be on fire or somthing.

If you allow costomers to make drawings and have alot of different options to make it look cool, theyll sit there for a long time making different pics and doing different options to see how there drawing will act.