In a way, the first Kaizo Mario game also has a True Final Boss of sorts. After beating Bowser (the final boss) in his castle, the credits start rolling. But through a secret exit in the Dead Sea level, you access four Special stages. The last special stage is a brutal castle level that ends with a room with no music and a crushing spiked ceiling. On the other side of a spike pit is the boss door that leads to the game's True Final Boss: a Bowser Statue.
The True Final Boss room was designed to be reminiscent of the Bowser battles from the original Super Mario Bros., but taken Up To Eleven with a maze of blocks, a Podoboo jumping out of the lava right where you drop into the maze, a spike on the ceiling to keep you from spin-jumping in to destroy a flashing Koopa shell, the Bowser statue's fireballs coming straight at you in the first horizontal part of the maze, rising and falling spikes that can kill you both directly and indirectly (by blocking your path), and if you somehow make it past the rising and falling spikes, you may still get ambushed by a Bullet Bill in the final narrow horizontal passage at the very end. And if you make it past all that, you access another Star Road that will take you to a new level, which is just the goal line, with a feather just before it. DO NOT GRAB THE FEATHER! Cross this goal line, and return through the Star Roads, and you will access the fall pallete, just like you get from beating the Special World in the original Super Mario World.
In a way, the first Kaizo Mario game also has a True Final Boss of sorts. After beating Bowser (the final boss) in his castle, the credits start rolling. But through a secret exit in the Dead Sea level, you access four Special stages. The last special stage is a brutal castle level that ends with a room with no music and a crushing spiked ceiling. On the other side of a spike pit is the boss door that leads to the game's True Final Boss: a Bowser Statue.
The True Final Boss room was designed to be reminiscent of the Bowser battles from the original Super Mario Bros., but taken Up To Eleven with a maze of blocks, a Podoboo jumping out of the lava right where you drop into the maze, a spike on the ceiling to keep you from spin-jumping in to destroy a flashing Koopa shell, the Bowser statue's fireballs coming straight at you in the first horizontal part of the maze, rising and falling spikes that can kill you both directly and indirectly (by blocking your path), and if you somehow make it past the rising and falling spikes, you may still get ambushed by a Bullet Bill in the final narrow horizontal passage at the very end. And if you make it past all that, you access another Star Road that will take you to a new level, which is just the goal line, with a feather just before it. DO NOT GRAB THE FEATHER! Cross this goal line, and return through the Star Roads, and you will access the fall pallete, just like you get from beating the Special World in the original Super Mario World.