SAm Steele the author of DreamZZt and DCFrotz has today released DCBlap a 3d pong game for the Sega Dreamcast, heres more details:

DCBlap is a 3d pong game for the Sega Dreamcast. It supports 0 – 2 players, the Dreamcast will play for any controller that isn’t plugged in, and controllers can be added / removed at any time. The first player to get 5 points wins. Pressing start during gameplay will exit the game. Depending on which version you use, it will either exit back to your boot loader, or to the Dreamcast’s BIOS menu.

Heres a screenshot

Check out his site http://www.c99.org/dc/index.shtml