Probably the Smash game I find myself coming back to the most on the merits of its singleplayer alone. Subspace is easily my favorite piece of Smash content we've ever gotten, even though we'll probably never get anything like it again. The core gameplay's pretty shit, but be honest, nobody's playing this game in 2021 for the core gameplay. (That, and I'd argue every Smash from this point on doesn't play that well anyway.)