In fact there was actually a fairly well-known app that Apple removed from the App Store about a decade ago that used the accelerometer to measure how high you could toss your phone in the air and catch it. Shockingly, this led to a noticeable spike in repair requests at Apple Stores, and the app was eventually taken down.
> "is it possible to turn your phone into a vibrator using haptics?"
Yes - there's about a hundred of these apps on the app store. Just, you know, make sure your phone is rated IP67.
Other feedback
Make sure the various games subscribe to resize events. I tried the Mario one, and when I maximized the browser window it left a huge blank area to the right.