No. Nintendo has never released Splatoon (1, 2, or 3) for Windows or any PC platform. It is a strict Nintendo Switch/Wii U exclusive. [1, 3]
It may ask for your phone number or "human verification" which leads to . [1, 3] It may ask for your phone
Any site claiming to have a native .exe file for Splatoon is almost certainly hosting malware, adware, or survey scams . [2, 5] How People Actually Play it on PC [4, 6] None
Players use emulators like Cemu (for Splatoon 1) or yuzu/Ryujinx (for Splatoon 2 & 3). [4, 6] or survey scams . [2
None. Cons: High risk of infecting your computer; the game won't actually work.
It is likely a or a "downloader" that will install unwanted software.
If a website offers a "free PC version" of a Nintendo exclusive: