Abstract: Disclosed are improved, unpredictably tumbleable capsule structures that are loosely internally provided with weighty rollable spherical ball, whereby such improved capsule is adapted to unpredictably compete with identical tumbleable capsule structures along downwardly-inclined ramps. Such improved tumbleable capsule structures are preferably circularly symmetrical about a directionally longitudinally extending horizontal central-axis and also about a central vertical-plane, and having uniquely ratioed capsule housing and interior rollable sphere interdimensional parameter values. Ancillarily disclosed are improved topically-textured and judicially-inclined racing ramps and ramp starting gates, all devoted toward enhancing unpredictable racing capability for a plurality of identically constructed internally-weighted tumbleable capsule structures along downwardly-extending ramps.