If you could play through all of Doom II using only the super shotgun without constantly running out of ammo you were playing on easy.
Okay, so while you can't literally use nothing but the SSG for the entirety of Doom II (especially since you don't get it until MAP02), you can comfortably use it at least 90% of the time on UV. Shells are plentiful throughout the game.
Doom II wasn't boring.
The Super Shotgun game
If you could play through all of Doom II using only the super shotgun without constantly running out of ammo you were playing on easy.
Okay, so while you can't literally use nothing but the SSG for the entirety of Doom II (especially since you don't get it until MAP02), you can comfortably use it at least 90% of the time on UV. Shells are plentiful throughout the game.