Your space in the ocean, invaded.
The earliest titles in Sega’s SG-1000 lineup skew heavily toward military realism and violent themes, setting the console apart from the cartoonish whimsy of Nintendo’s first-party catalog for Famicom. However, while approaching Sega’s library in order of catalog number suggests a huge block of war games at launch, contemporary reporting places the release dates for several of those low-numbered titles further out, meaning prospective consumers didn’t actually find themselves bombarded by militaristic fare on day one. Of the system’s launch titles, only N-Sub and Yamato (a pair of naval shooters that alternately place players above and below the water’s surface) fall under that heading.
As N-Sub’s title suggests, this game sees you shuffling around in a tiny submarine, dodging torpedoes and depth charges while taking potshots at enemy forces skittering along the ocean’s surface. N-Sub (presumably an abbreviation of “nuclear submarine”) hails from arcades, where it initially appeared in late 1980 as a somewhat tardy title in the Space Invaders style—another in a seemingly endless array of shooters from the late ’70s and early ’80s to fall into the Space Invaders format. At the time N-Sub’s arcade cabinet made it debut, Japan’s Invaders mania had just begun to wind down, supplanted by more advanced or complex shooters like Namco’s Galaxian.
N-Sub began life as a title for Sega’s VIC Dual system. A plug-and-play cabinet, the VIC Dual platform shared a great deal in common with Data East’s tape-based DECO format and Nintendo’s VS. System. Sega’s platform applied this principle in order to allow operators to install two different titles in the same arcade cabinet, determined by a pair of plug-and-play ROM boards specifically designed for the machine. Co-developed by Sega and its fully-owned American distributor Gremlin (which Sega would sell to Bally Midway around the same time that the SG-1000 debuted in Japan), the VIC Dual ran on an architecture that shared some of its technical specs with the SG-1000 hardware. As such, it made perfect sense for many of those titles to be converted for the home platform.
N-Sub, unsurprisingly, makes for a pretty faithful arcade conversion, although it loses some visual information in translation. The arcade system ran on a vertically oriented screen, so the visual layout had to be converted to work on 4:3 consumer televisions. Despite this change, the SG-1000 port sticks closely to the original work. Players control a submarine that can maneuver freely through the lower third of the screen, which represents an underwater space. N-Sub applies a bit of visual perspective to its rendition of the ocean: Ships in the foreground appear larger (and therefore are easier to hit) than those in the background. Despite its basic visuals, small grace notes like these elevate it beyond a bog-standard Invaders clone. The sub can fire torpedoes straight ahead as well as upward toward the surface, the former allowing it to defend itself from enemy forces below the water—namely other subs—while the latter lets you destroy surface patrols, which attempt to hit your sub by dropping depth charges. The goal of each wave is to completely clear out a fleet of rival ships on the surface.
Once the player wipes out an entire fleet twice, a quartet of destroyers enters the fray and circles around on the water’s surface, dropping depth charges as they sail around. Take out the destroyers and you move along to the next wave, where the action moves a little faster and enemies adopt a more aggressive stance. As the player flits about underwater, the enemy’s navy keeps things tense by sending a variety of anti-sub forces after the player. Submarines move in erratic forward patterns, launching torpedoes straight ahead any time the player crosses their line of sight. The enemy fleet fires torpedoes downward as it advances, while large yellow homing bombs will occasionally plummet downward from the sky. Finally, the most dangerous foe is the “Mystery” boat, clearly inspired by Space Invaders’ “Mystery” saucer. Rather than simply streak along at the top of the screen as a passive presence that lacks the ability to harm the player, however, the Mystery boat zips quickly along at the front edge of the water. Once it passes over the player’s position, this enigmatic PT boat attempts to box in your sub with a pair of depth charges. In later stages, this explosive pair becomes a trio and eventually a quartet, further increasing the difficulty level of the action.
Throughout the entire game, your sub can only patrol the lower third of the screen and fire single projectiles in two directions. The option to maneuver along the y axis and fire along the x makes for a more nuanced game than its inspiration Space Invaders, but the lack of any sort of upgrade chain or bonuses beyond extra points for effective hits roots this firmly in the late ’70s tradition of Invaders-alikes rather than placing it the contemporary company of more evolved shooters like Namco’s Galaga or even Sega’s own Star Jacker (which technically featured power-downs rather than power-ups, but close enough).
That’s the extent of what N-Sub has to offer, really: Shooting down the same formations over and over again as they grow ever faster and launch more and more projectiles at you. Meanwhile, your sub never grows more powerful or gains new capabilities. It makes for something of a stagnant play experience, but for a game of this vintage, it’s not entirely unreasonable— good enough to remain engaging for repeat play, at least. N-Sub requires a bit of skill, but it’s not as heavily stacked against the player as most shooters of this era. Once you get a feel for the patterns, you can realistically keep a single credit going for 10 or 15 minutes. And, despite the simple design, the enemy subs and PT boats behave with just enough randomness to prevent the whole thing from feeling mechanical or rote.
DUAL OF THE FATES
Sega’s Video Interface Chip Dual system represents a significant milestone in video game history: The future first-party giant’s first proper attempt at creating a standard arcade platform, created in collaboration with San Diego-based Gremlin Industries. Sega had previously made use of Gremlin’s Blockade hardware, and the two companies developed the VIC system together—a venture that seemingly proved so fruitful that Sega acquired Gremlin in 1978, a year after the first VIC-based game (Safari, a simple precursor to Safari Hunting) debuted.
VIC Dual, so named because the cabinet could house two games, helped bring Sega’s arcade offerings into the world of modern-day computing tech. Prior to their creations for the Blockade and VIC hardware platforms, Sega built games around discrete logic chips rather than microprocessor-based boards. The move to CPU-based tech turned the process of game creation into one of software programming rather than of pure engineering, which reduced development costs and greatly simplified the process of bringing games to other platforms—such as the SG-1000, which used a different version of the Zilog Z80 chip that operates as the beating heart of the VIC Dual chip set.
Sega & Gremlin’s Carnival
The VIC Dual system actually evolved over the course of its lifetime: Sega’s earliest creations for the platform offered only simplistic monochrome graphics and relied on cabinet overlays to help convey their imaginary worlds. For example, Frogs—often cited as an early take on the platform action genre—really only used its graphical output to display the player’s frog character, the moving flies they needed to catch, and the running score tally. The rest of the game setup, including the lily pads players needed to leap between, only existed as overlays.
Before long, however, the VIC hardware grew to offer a beefy 64-color palette and the ability to display fairly complex moving graphics. Several early SG-1000 releases made their debut as VIC Dual titles, and all of them looked crisper and more detailed in the arcade. N-Sub, for example, presented its sea and sky environments with a sophisticated (for the era) gradient effect that conveyed the impression of murky ocean depths… an effect that the humble SG-1000 couldn’t effectively reproduce. Indeed, Sega had already retired the VIC Dual format by the time the SG-1000 debuted, moving along to the advanced VCO Object and System 1 platforms. But the appearance of so many VIC-based games on the console makes SG-1000 a welcome tribute to Sega’s primal arcade efforts.
Yamato (arcade version)