A neon graffiti wall. Drag to burn a thick glowing stroke — the previous→current pointer segment is stamped as a soft capsule into an accumulation buffer that fades and blurs each frame, so paint blooms then dissolves. Hue drifts along the stroke and brightness tracks your speed, with additive glow and a chromatic fringe on the freshest paint. Left alone, a virtual hand writes looping calligraphic gestures with pen-lift pauses.