You play volleyball, 2D side view.
But everyone controls a vertical stack of multiple (tiny) people.
Each player gets one button.
When pressed, your entire stack jumps up at once (then automatically falls down due to gravity).
So it’s like foosball (table soccer), but made vertical and volleyball!
I envisioned a kind of Totem, Maya/Aztec, Mesoamerican visual style for this. (The stack of tiny people is a totem, for example.)