Log message:
games: add 3dpong

3D Pong is a one- or two-player, three dimensional sports game, based on
the first arcade game ever made, "Pong" from Atari. Each player controls
their "paddle" with the mouse, and tries to score by bouncing a ball into
the other player's goal (just behind the paddle).

3D Pong is a vector-based graphics X-Window game for Unix.