Before Sonic, Sega was a company in dire need of a mascot. Their games were successful in the arcades, sure, but there was merchandising money to be made, and Nintendo had Mario, Namco had Pacman, etc. So Sega tried out a few mascots, and the first to really take hold was a small boy named Alex Kidd.
Before Alex Kidd, Sega's mascot was the character Opa-Opa from the arcade game Fantasy Zone, but once Kidd popped up in his first game he was a hit. His first game is one of his best, Alex Kidd in Miracle World which was released for the Master System in 1986.
Miracle World is a colourful platformer intended as Sega's answer to Super Mario Bros, and it does do the job quite well. It's well-designed, looks nice, and has some excellent music and sound. It does lean a little too heavily on chance elements (you play *a lot* of rock-paper-scissors), but it's a solid game nonetheless.
Next up is Alex Kidd: The Lost Stars which came out in the arcades as well as on the Master System. The Lost Stars looks very nice, especially the arcade version, but it's a pretty uninspired outing on the whole. Unfortunately, The Lost Stars is closer in quality to most remaining Alex Kidd games than Miracle World.
Alex Kidd: High-Tech World is next, and the final Alex Kidd game for the Master System for now. This one is considerably worse, an inferior game that was being developed concurrently to The Lost Stars that had Alex slapped on top of it when the previous game was a success. Not fun to play in the slightest.
By this time, though, Alex was a recognizable figure in the video gaming world, particularly in Europe. Master Systems were now being sold in Europe with Alex Kidd in Miracle World programmed directly into the system, so a lot of people in Europe were introduced to video games as a whole by the cuddly Mr. Kidd. And when the 16-bit consoles arrived, Alex Kidd made the move with them.
Alex Kidd In The Enchanted Castle is Kidd's only 16-bit excursion, and unfortunately the game is pretty cruddy as well. The controls are some of the worst in the series, the graphics are barely a step up from his 8-bit excursions, and there is so much more rock-paper-scissors. Nothing unfairly ups the difficulty of a game by constantly losing lives through dumb luck. Aggravating, terrible design. But before being dropped by Sega, Alex had one trick left up his sleeve.
Alex Kidd in Shinobi World is the best Alex Kidd game, and it's not really a full Alex Kidd game. It's a parody of the excellent Shinobi, Sega's ninja side-scroller arcade hit. The mash-up is quite cute, with Alex Kidd fighting the rough and tumble ninja baddies of Shinobi. The game is great, feeling more like a successor to Shinobi than to any one Alex Kidd game.
But in 1990, Sonic arrived. And once Sonic arrived? That was it for Alex Kidd, who was then relegated to the occasional cameo in Sonic properties and Sega all-star games. A likeable enough placeholder until Sega got the real deal, I suppose. Poor Alex Kidd.