The DUPLO invaders in The Lego Movie 2: The Second Part come from the Systar System.
The Systar System is the colorful galaxy-dimension explored in the 2019 sequel. It is home to Queen Watevra Wa'Nabi, General Sweet Mayhem, the DUPLO aliens, and many of the film's musical and fantastical characters. Emmet travels there after Sweet Mayhem captures Lucy and his friends.
The name is a play on “sister,” linking the fictional setting to Bianca, Finn's younger sister in the live-action framing story. Bianca creates the Systar System from her own toys and imagination, while Finn's LEGO creations form Apocalypseburg. Their conflict is presented in the LEGO universe as repeated attacks and escalating chaos.
The DUPLO characters initially appear to be destructive aliens, but the sequel gradually reveals that the apparent invasion reflects a misunderstanding between siblings. The worlds eventually combine into Syspocalypstar, blending Apocalypseburg with the Systar System. Systar System should not be confused with a real astronomical star system or with the unrelated fictional options listed in the quiz.