SEGA's masterpiece on the Master System, Dragon's Trap is a near-perfect platform adventure that mixes in light RPG elements as the icing on the cake.
I had greatly enjoyed Wonderboy in Monster Land, but was always frustrated by its timer and hurried nature (understandable, given its arcade origins). Dragon's Trap got rid of the linear format and laid open a world to be explored at leisure. Here were a variety of wildly different environments, challenging the player in different ways and containing plenty of secrets. The stuff of great adventures.
But the real stroke of genius was in the decision to have Wonderboy cursed and transformed into various forms throughout the game. Each form having unique abilities that allowed the player to access the level specifically designed for it, for example Mouse Man being able to stick like a spider to a particular type of block, or Lion-Man being able to slash downwards with his sword, breaking blocks below him. This Metroid-like mixture of abilities gave the game a superb freshness throughout with new challenges, and offered plenty of scope for exploration as a new form gave access to previously inaccessible rooms or areas. These would usually hold some kind of item or cash reward for players savvy enough to find them.
Like Super Mario Bros. 3 on the NES, Dragon's Trap really proved what could be done with the Master System in capable hands. It's bright and detailed, the enemies and different forms of Wonderboy superbly designed and full of character, and the areas are complemented by a range of great tunes, my favourite being the island music Side-Crawler's Dance.
It's an eternal source of sadness to me that SEGA didn't keep up the Wonderboy series and build on the promise of this classic. A couple more installments appeared on the Megadrive, but the character and even the style of game faded away. With the continued success and obvious popularity Metroid and Castlevania I can't help but think that SEGA let a really good thing go to waste.