How do I transfer this game to another devise

Follow the instructions in this support article to redownload apps and games from Apple --> Redownload apps and games from Apple - Apple Support

If you have iCloud set to sync, app data should transfer. If your data is on the developer's site, logging into it should get it.

Multipledevices123 Said:

"how do I continue my existing game on another devise"

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Troubleshooting Game Transfer Issues:

You might not able to use this on another device. Newer versions of iPodOS may be required, or the developer has yet to do their part in making it compatible with the iPadOS currently installed.

Some games have accounts that can share progress across several devices.