PC Booter or Boot Loader is a general term for software that runs on early IBM PCs that require you to boot directly into the program rather than first booting into the operating system. This practiced was followed in order to have access to precious computer resources that would otherwise be used by the OS. Many games produced for IBM platforms in the early 1980s were PC Booters.
Although many non-IBM platforms also supported booting from a disk (Apple II, Commodore 64, etc.), this was the expected behavior for those platforms, so a special term is not needed to distinguish software on those platforms.
I never owned an IBM or compatible PC where boot loading was common, but I have used them, and many IBM compatible PCs that I used continued to support boot loading long after it was necessary.
Sadly, the early IBM PC was a terrible platform for gaming, so there just weren't that many fun games released for this platform. Most of the good games at the time were released on the Commodore 64.