I'm pretty sure that the emotions here are a reference to Super Princess Peach. The commentary uses the word "εζεζ₯½," or kidoairaku, for emotion instead of the much more common "ζζ ." Each of the four kanji in kidoairaku corresponds to one of the Vibes in Super Princess Peach (and here): ε for Joy, ζ for Rage, ε for Gloom, and ζ₯½ for Calm. Plus, the Vibe Gauge in the Japanese version of SPP is called "εζεζ₯½γ²γΌγΈ", so yeah.
Which brings up a question: Does an image count as a crossover if it shows gameplay mechanics, but no character? I know that it counts for UI stuff, like in this comic by goma (gomasamune), but I don't think I've encountered direct references to gameplay mechanics themselves before, at least not ones unaccompanied by some UI element.