To play this on a modified Nintendo Switch, use an installer like DBI or Tinfoil.
This specific file name suggests you are dealing with a for a Nintendo Switch game backup. To use this file, you need to combine it with its matching parts to extract the playable game file. How to Extract and Use the File Sonic Colors Ultimate (NSP)(Base Game).part2.rar
Ensure you own a physical copy of the game before downloading or using backup files to comply with copyright standards. To play this on a modified Nintendo Switch,
Do you have of the archive downloaded in the same folder? Sonic Colors Ultimate (NSP)(Base Game).part2.rar