This is a 2-player talking game which can award both replays and extra balls for high scores. A spinning target marks each end of a large horseshoe lane that runs under a raised center ramp. A fast ball in the horseshoe lane comes out the other side. A slower ball might disappear under the ramp and exit play. A timed multi-ball mode allows up to six balls in play. A second button on each side of the cabinet next to the flipper buttons gives the player the choice of ball entry onto the playfield to either the left or right flipper. Some game sounds are also found on Williams’ 1980 ‘Black Knight’ and Williams’ 1981 ‘Hyperball’.
Thunderball’ never went into production. Williams experimented with having drop targets on the upper ramp before deciding on standing targets, and one game with this variation has been seen by an IPDB Editor.
James T. Hawes, technical writer and technical support technician at Williams, wrote content for and assisted in the design of four backbox toppers for this game. He contracted with a local art studio for the final pieces. They were a simple tent-shaped sign made of Fome-Cor. The front showed multi-colored “bullet points” (text) on a black background.
Hawes was firm in his recollection that there were exactly four toppers made, to promote four test games that were put out on location, one topper for each, but he believes Williams likely made engineering samples of Thunderball as well.
Source: Internet Pinball Database