The time gates in Chrono Trigger have a distinctive swirling blue portal effect. This shader recreates that look using layered sine waves, procedural hash noise for texture, and a spiral distortion centered slightly off-axis. The color gradient shifts from deep blue at the edges through cyan to near-white at the peaks, with a soft vignette that fades the portal into darkness at the rim.
The effect pixelates the output to 6x6 blocks for a retro SNES feel.