using apps removed from the app store
So if I have a game I downloaded and installed on my iPad and sometime after the app is removed from the App Store, can I still play the game on my iPad since it is already downloaded and installed?
Yes, you can for as long as the app remains installed and is compatible with your installed iPadOS version.
Be aware, however, that apps are not part of any backups. Only app data is backed up. What this means is that if you ever have to restore your device from a backup, the apps that can't be re-downloaded from the App Store, will be gone.