If you've not been able to find the Purchased page in the App Store app since updating to iOS 11, don't worry - the page is still there, it's just moved.
- Open the App Store app.
- Make sure you're in the Today tab. The Today icon on the left of the bottom bar should be highlighted - if it isn't, tap it.
- Tap the circular picture at the top right of the screen to open the Account page.
- Tap Purchased, then My Purchases.
It's as simple as that.
There's a search box at the top, which we highly recommend because your list is likely to be enormous. (The search query doesn't just apply to the name of the app - it will also pick up words in the description, so searching for 'game' will do the trick.) And you can choose between viewing all your purchased apps, or just the ones that aren't on this device.
Purchased page in iOS 10 and earlier
The Purchased page often comes in handy for redownloading apps that have been removed from the App Store. In iOS 10 it lives on the Updates tab: it's much easier to find there.