So Wikipedia has an article on killer apps and includes Sega hardware: https://en.wikipedia.org/wiki/Killer_application#Video_games I'm trying to expand the list, but other examples I can think of such as NFL 2k and NiGHTS, I can't really find any valid sources claiming they boosted hardware sales. Would be curious if anyone here had some input.
I feel like I remember reading that Dreamcast kiosks running Soul Calibur were fairly instrumental in demonstrating why the Dreamcast was an essential purchase, more so than Sonic Adventure [citation needed] There must be a killer app for the Mega CD that demonstrated why FMV games were the future - Night Trap? I feel like the master system version of Sonic probably revived and kept the master system relevant during those early years when the Mega Drive was more expensive. Probably also the Game Gear's killer app? Not sure. Funny that the list doesn't mention Donkey Kong Country for the SNES. DKC is probably the only reason why the SNES clawed back credibility during the 16-bit wars, otherwise the Mega Drive would have been a runaway success. Also, list doesn't have DOOM (pushed IBM-comp PC sales) or Quake (pushed early adoption of GPUs)