SWIV is a vertical scrolling shooter and an unofficial follow-up to Sales Curve's conversion of the side scroller Tecmo arcade game Silkworm.
One player controls a helicopter and the other a jeep, with the jeep transforming into a boat when the vehicles pass over water. As well as a host of blaster fodder the game also includes a mid-level enemy inspired by the "Goose" enemy from the earlier title Silkworm. Pieces of this enemy would fly onto the screen and assemble into one vehicle before commencing to fire at the players' vehicles. When destroyed the "goose" would drop power-ups.