One of the most curious licensing phenomena of the 80s was the exclusive sequel to an arcade game. Manchester’s Ocean Software specialized in the trick, creating follow-ups such as Target: Renegade and Yie-Ar Kung Fu 2. However, as the 1990s dawned, a general tightening of licensing laws led to the appearance of less home-exclusive suites. Instead, inspired by an official arcade conversion hit, a company expanded its remit into a spiritual sequel, creating one of the best shoot-’em-ups of the time.
The developer-publisher The Sales Curve was created in 1988 by Jane Cavanagh, a former employee of Telecomsoft. “Between 85 and 88, I frequently traveled to Japan on behalf of Telecomsoft, negotiating the sale of our titles in Japan and buying licenses for arcade games,” she recalls. “Even though the industry was at a fairly embryonic stage, through my travels to Japan, I became convinced that it would be huge.” Cavanagh’s belief in the games industry compelled her to leave Telecomsoft and start her own company, The Sales Curve, initially to help others with licensing, product development and distribution. “In the first year, however, we started developing our own titles and self-publishing.”
One of Cavanagh’s contacts was a coin producer named Tecmo. Tecmo had occupied the second tier of arcade game manufacturers before the popularity of side-scrolling shoot-’em-ups such as R-Type and Gradius thrust its 1988 game, Silkworm, into the limelight. As a result, Silkworm topped Cavanagh’s list of potential arcade games to license. “It was relatively easy because I already had a good relationship with Tecmo – then I just had to bring the creative and management teams together,” she says. Under the Random Access banner, the team at The Sales Curve initially focused on 16-bit games.
Part of this creative team was programmer Ron Pieket. “Silkworm was a surprise hit,” he tells me. “The Sales Curve were a relative newcomer to the scene, and that really put them on the map.” From the Commodore Amiga to Amstrad CPC, Atari ST, Commodore 64 and ZX Spectrum, every release of Silkworm was a critical and commercial success – a rarity for arcade conversions in the 80s, with at least one port almost always turning up to be a shit. Capitalizing on the success of Silkworm became a priority for Cavanagh, but there was only one small problem: Tecmo hadn’t actually made a sequel to the arcade game itself. So if The Sales Curve went ahead with another Silkworm game, they couldn’t call it Silkworm 2 and were understandably reluctant to pay Tecmo just for that honor. “But that meant we had complete artistic freedom,” notes Pieket, “and since we were fans of vertical-scrolling games, this decision was made easily.”
Artist Ned Langman partnered with Pieket on 16-bit games. “We all loved Silkworm, and it had been described by some critics as better than the arcade original. Jane was so happy she wanted to use the same team to work on something new. We were also fans of the scrollers top-down verticals such as Xenon and Battle Squadron, so we wanted to do something like that.” In honor of its inspiration, the working title for The Sales Curve’s next game has become Silkworm 2. “We all searched for an original name, and various ideas fueled it to become SWIV,” Langman continues. “It’s still a mystery as to what exactly that means!”
The name SWIV, a charming acronym with nebulous origins, became the focus of its advertising campaign, frequently mentioned on the pages of gaming magazines. According to the intro of the game, it depicts the slightly awkward Special Weapons Interdiction Vehicles. “It was a spiritual sequel to Silkworm, and we thought it was so advanced we should call it Silkworm 4 – after skipping two and three!” laughs Cavanagh. Other renditions included Silkworm In Vertical and Sold Without Virgin Interference – a tongue-in-cheek reference to The Sales Curve’s former distributor, Virgin.
But there had to be a decent game behind the hype and the name. “The design was a collaboration between Ned and myself,” recalls Pieket. “And the first thing I did was develop the level editor.” Pieket and his colleagues were keen to give SWIV a special look and create a fresh shoot-’em-up. “While virtually all games at the time used tiled backgrounds, the SWIV editor was sprite-based. This gave the game a very unique look.” Another benefit of Pieket’s system was the ability to create large maps – in the case of SWIV, one very long map for the entire game.” The editor allowed Ned to place color palette changes that scrolled in synchronization with the background, powered by the Amiga’s Copper chip. That way we could create a single board that still had color variations as the game progressed.”
The Copper – essentially a coprocessor buried in one of the Amiga’s chips – proved a valuable ally to designers such as Pieket and Langman. “The different areas had defining themes,” he recalls, “but they blended into each other as they went by. It was difficult to create the maps with the constantly changing color palette; if I couldn’t get the colors to blend from theme to theme, sometimes I just masked the change with backgrounds made up of sprites.” Dubbed Dynamic Loading System by The Sales Curve and used at promotional purposes on its packaging, the continuous, non-stop action of SWIV (in its 16-bit versions) was a major selling point. “It was a real technical feat,” says Cavanagh. “The illusion of a single uninterrupted attack, the equivalent of 236 screens without data access breaks.” Fortunately, an adaptive difficulty level, based on time played without losing life, helps players navigate through the relentless wave of enemies.
Langman and Pieket’s efforts have produced a sleek, beautiful, and fun shoot-’em-up that owes the Tecmo classic some debt. According to Langman, “The ‘Goose Copter’ was basically a copy of the boss Silkworm. Various small helicopters come together to form one large ship. The look was different, but the idea was the same.” And like the previous game, two players can play simultaneously, one at the controls of a helicopter, the other a rugged jeep. With the freedom to develop their game away from the restrictions of an arcade license, references to Thunderbirds and other arcade games – such as the old Namco game, Xevious – were introduced. Often cited as one of the greatest shoot-’em-ups on the Commodore Amiga, Andrew Barnabas’ upbeat music became the icing on the cake, alongside an impressive schematic design of the vehicle during its intro. “Oh yes, I’m very proud of those!” Langman smiled. “I think the opening credits of Terrahawks swayed me, and that’s a really cheap trick. Each layer of the vehicle is drawn in a color from the palette. All the colors were then turned black, then green one at a time. Simple but effective!”
Released in the spring of 1991, SWIV received rave reviews in the 16-bit press. “Gorgeous graphics, sound that goes beyond the functional, and that elusive ‘one more try’ factor make SWIV an essential purchase for blasting fans,” said The One magazine. The only dissenting voices generally cited SWIV’s high difficulty level. “It got relentlessly difficult later on,” admits Langman, “but it was very playable if you ramped up your firepower properly and got into the zone. I was always really happy with what we did – we had certainly a lot of ideas that we never had time to put together.” Handsome, humorous (alien ships leave crop circles, shopping carts litter empty river beds) and inventive, SWIV already had enough ideas for a dozen games.
Beyond the good reviews, it was SWIV’s sales that had the biggest effect, especially for its fledgling publisher. “The success of SWIV – and Silkworm – has been hugely important to The Sales Curve,” Cavanagh reveals. “These titles and the creative team behind them really launched the company.” Five years later, The Sales Curve became SCI Entertainment Group and floated on the London Stock Exchange. These small jeeps and helicopters from Silkworm and SWIV have forged its success. “I have very fond memories of that time,” Cavanagh says. “It was very early for the company and very exciting. To have two first hits was just amazing – I’m especially proud of them and grateful to the team that created them.” The success of SWIV has also defined the careers of its developers, as Pieket recounts. “SWIV has been essential for me: its popularity has opened many doors for me, and I still get ‘Oh my God, did you write SWIV?’ comment.” And finally, for Ned Langman, it’s a love that never quite disappeared. “I never gave up on SWIV because it was the most fun game I’ve ever had making a game!” he smiles. “Maybe one day I’ll get to this unofficial follow-up…”