Search for KB3033055 . This is the official "patch" that makes RT 8.1 look like Windows 10.

Running classic games through DOSBox or specialized handheld emulators. Risks and Technical Barriers

provides links to community-verified images for various RT devices. Microsoft Support (Official Recovery)

If you want to play with Windows RT today, learn to apply the jailbreak yourself using verified scripts from GitHub (where the code is open to inspection). Leave the mysterious patched ISOs for the digital archaeologists.

There are several reasons why users might need a patched ISO of Windows RT 8.1:

If you find a file named Windows_RT_8.1_Patched.iso on a torrent site or a random file locker, proceed with extreme caution.

"Windows RT 8.1," he muttered, tracing the Windows logo. "The beautiful dead end."