The SG-1000 was Sega's first attempt at a home console, but it was an ill-fated project. Already technologically outdated upon release - it hit shelves in Japan on the very same day that the Famicom did - it mostly served as a platform for hopeless ports of Sega's arcade hits. There were some MSX games, but the home computers profited more from the similar system specs of the two. It only had a handful exclusive titles, and most of those were obscure Japanese pachinko, mahjong or board games. All the system was really notable for were a couple of original shoot-em-ups, Yuji Naka's debut Girl's Garden, and Dragon Wang.
The title might seem mildly indecent to English speakers (on the status display it's shorted to D-Wang, which has only gotten more awkward in time), but Wang is actually the family name of the Chinese protagonist, a shirtless kung fu fighter on a quest to Get the Girl. The action in the game is an homage to Bruce Lee's Game of Death, or maybe a rip off of Irem's Kung Fu, which is also an homage to Game of Death, despite its Jackie Chan license.
Like in those two titles, the hero enters a dark tower full of martial arts fighters, but the structure has been mixed up a bit. Instead of fighting a major opponent on each floor, Dragon Wang has to jump up and down between them to get through a maze and find the big bads in each round, mowing down countless mooks on the way. Like in Kung Fu, these consist of unarmed guys and knife throwing cowards. They're not quite the life-sucking killers as in Irem's game, but can get dangerous nonetheless, even though they all go down after a single hit. Timing is very important when fighting them off with Wang's mighty foot - cause fists are for sissies, he just kicks the shit out of everyone.
The levels are mostly just samey-looking corridoors in front of black nothingness. Whenever Dragon jumps through a hole in the floor or ceiling, all his enemies explode. There are also some annoying hidden trapdoors to set him back. The most exciting parts are the occasional shutter doors that have to be kicked open, all the while the enemy hordes keep on attacking.
All this of course is only staged to wear down his energy for the bosses, who guard the keys to the level exit and can be approached in any order. In the first stage there are three of them, but one more gets added with each following round. The first few are just martial arts movie stereotypes like "guy with nunchucks" or "guy with a stick." Eventually, though, Wang gets to fight the "Warpman" who suddenly appears anywhere on the screen for a surprise attack, and a laser-shooting robot! The final boss, called Jonathan, is just a cheating asshole and pretty much impossible to beat, even though he appears to be just a pair of pants.
It doesn't really matter if you never get past him, though. Dragon Wang is out to get his love Kyoko from the dark tower - who might've been kidnapped by the villains, or just happen to live there, it's never really told. At any rate, "Only with true love can you become her hero! Try next round!" But it's all a lie. D-Wang will never become her hero, and he's stuck inside the tower forever. Once he clears the fourth round, the same stage just repeats over and over again.
If you thought Zombie apocalypse spin-offs of established franchises were a new trend, look no further than Kung Fu Kid to find your preconceptions shattered. Wang may have lost the right to appear in the title (the Japanese one translates to "Spirit World Chronicles"), but he's still mentioned by name in the game's description. And he bought himself a shirt.
The same formula of making one's way through the area by kicking the endlessly respawning fodder enemies into oblivion returns, although the stages are now linear, and thanks to the graphics power of the Master System much more pleasant to look at. The level designs seem almost more primitive than in Dragon Wang, and most of them only require Wang to run from left to right, using his feet to dispose of anything that gets in his way. Some of the later stages require a bit of platforming, but even though Kung Fu Kid is one of the very first games to employ a wall jump mechanic, it's all perfectly straight forward and devoid of any sense of exploration. Wang's jumps at the time are extremely floaty, launching him in the air for almost the entire height of the screen, so the platforming never feels particularly challenging, either. There are a few hidden items to find, but half of them are just health refills, while others, like a potion that turn's Wang's hair purple, don't seem to actually do anything useful.
Generic hoodlums are still among the attackers, but the enemy's main forces now consist of the undead. Although most enemies fall into the greater category of "traditional Chinese zombies," there's a lot of variety in fighting them. There are hopping zombies (like those in Super Mario Land), tiny zombies that shoot their arms at Wang, and green zombies that can only be destroyed by magic - Wang's feet are still his premier weapon, but to counter the hordes of the undead he also picks up charms that can then be sent flying to set everything in their way on flames (except for the bosses, who are uniformly immune to them). In some stages Wang is attacked by small enemies like lobsters(?) and frogs, and kicking them turns them into deadly projectiles for some reason.
Suitable to the game's theme, the major opponents at the end of each level reach from wizards and flying ghosts to club-swinging ogres and all the way to giant toads. Towards the end await a few more conventional martial artists, and at two points Wang has to fight twin enemies at once. Most bosses have some blind spot he's best advised to exploit, but it's not enough simply to be better than them - Wang also has to balance out the handicap by the wounds he's been dealt throughout the stage. Like in the first game, regular enemies are not very likely to actually stop him, but getting to the end with a majority of the health bar intact is very difficult. When losing a life, even during the boss fight, Wang always starts from the very beginning of the stage. This becomes increasingly painful as the player progresses through the game, especially in stage 6, which exclusively consists of a massive 5-part boss rush.
While Kung Fu Kid has the difficulty of a Castlevania or a Ninja Gaiden, it decidedly lacks the finesse and perfection rank among the truly great action platformers of its time. In the arcades, Sega's own Shinobi and beat-em-ups like Double Dragon had all showed new directions for the genre to go in, leaving Kung Fu Kid lying in the dust like a relic of ancient times. It's by no means a bad game; it has servable mechanics, a few unique gameplay elements, cool enemies and an interesting premise. But in the case of Kung Fu Kid, being decent was not good enough, and so it went generally overlooked and forgotten. With just a little more inspired level design, more polish and somewhat expanded length, it could have been Sega's answer to Castlevania.
The game did get a second life in Brazil, though. It was one of the titles Tec Toy salvaged when they got hold of some profitable cartoon licenses in the mid-90s, and thus Sapo Xulé: O Mestre do Kung Fu was born. This version replaces Wang with the eponymous, terribly animated frog, but otherwise remains exactly the same game - which makes things a bit awkward when Sapo gets to fight the "normal" frogs in stage 3.