This is the modern version available via Apple Arcade. It features a great mix of Namco originals, anime themes, and pop hits. Since this requires an active subscription, finding a "standalone" IPA for this version is difficult and often enters a legal gray area.
If you manage to find a Taiko no Tatsujin IPA from a community archive, you cannot simply "open" it on your iPhone. iOS is a closed system, so you need specific tools to install unofficial files. taiko no tatsujin ipa
Versions that might include custom songs or unlocked content. Popular Mobile Versions of Taiko no Tatsujin This is the modern version available via Apple Arcade