A terrarium is a micro‑chessboard. Put the dominant plant—think of it as the king—in the center, something that can thrive alone but supports everything else. Around it, place taller, sturdy species like rooks; they give structure and shade. The quick‑growing, low‑profile ones act as pawns, filling gaps, cycling nutrients, and attracting beneficial insects. Remember to layer moisture: a water‑retaining layer at the bottom, then a drainage layer, then a soil layer that holds the rest. Each “piece” should complement the others—some attract pollinators, some fix nitrogen, some break down waste. If you keep the roles clear and the spacing tight, the whole thing will move in harmony, just like a well‑played game.