Triangle Strategy -0100cc80140f8800--v262144--u... | Essential |

If you strip the dashes and letters: 0100CC80140F8800262144U

This is the most telling clue. The ellipsis indicates truncation. The original string was longer but got cut off by:

Likely original full string:
TRIANGLE STRATEGY -0100CC80140F8800--v262144--U--saveSlot0.bin TRIANGLE STRATEGY -0100CC80140F8800--v262144--U...

If you encountered the string as an error message in an emulator:

If you found it in a modded Switch:

If you saw it on a shady ROM site:

Requires specific choices:

Unlike Fire Emblem: Three Houses, Triangle Strategy has: