While not a typical RTS game I believe They Are Billions could've been a much much bigger hit than it is and it's closer than you may think.
It has decent foundations, it changes the formula a bit, it is more focused on city-building and turtling than regular rts, it has superb music and it looks all right. People loved skirmish mode (despite game being extremely difficult with no saves), ironically the thing that was a nail in the coffin is the thing that should've been the crown jewel of this game: the campaign. If they made sound mechanic more obvious, decreased the difficulty and made an actual good campaign this could've been a cult classic.