Dark Taizo (ダーク泰三) known as Dig Dug Rival (ディグダグライバル), is the dark and evil version of Taizo Hori, he appeared in Dig Dug Arrangement on Namco Classic Collection Vol. 2; call him Rival for short.
Dark Taizo has the same ability as Taizo, he has a same device like Taizo's Harpoon-Drill. He can dig any direction like Taizo, if he see the real Taizo, he'll shoot his drill at him and pump him till he pop!
Rival's helmet is purple with a red horn on it,and a green drill, he's like a reflection from the mirror from the glass of obsidian.
If Taizo shoot his Harpoon-Drill before Rival do, a button appeared above them pushing at each other to get through him. Since Rival use to be Taizo's twin, but now if they reflect himself. When he being the real Taizo.