Meh, I grew up playing all the Turtles games as two-player only. Turtles/II on NES, Turtles HyperStone on Mega Drive, Turtles in Time on SNES... Only two-player.
Know what? We often had a few people looking on. Taking turns on each level. Two people played, two watched and dissed. And hey, it was more fun than a stick!