World 6-4 (Super Mario Bros.)

World 6-4 is the fourth and final level of World 6 in Super Mario Bros., taking place in a castle.

Layout
This level's layout is similar to World 1-4's, though with additional Fire Bars and Lava Bubbles.

The player starts the level on an elevated area with stairs heading downwards, ending at a pit of lava. Afterward is a platform surrounded by Fire Bars and Lava Bubbles, and with a ? Block containing a power-up above it. After a corridor of Fire Bars on the ceiling, there is a room with more Fire Bars placed on both the ceiling and the floor. Next is a room containing several Hidden Blocks before the bridge with the Fake Bowser, which has a Lava Bubble jumping up from below and a horizontally moving lift above. Fake Bowser also starts throwing hammers.

Super Mario Bros. Deluxe challenges
In Super Mario Bros. Deluxe, the player can collect five Red Coins, find a hidden Yoshi Egg, and get a medal based on their score. The Yoshi Egg is found in a Hidden Block directly to the right of the first Fire Bar, and the score to beat is 12000. The Red Coin locations are:
 * Above the lava pit to the right of the ? Block
 * Above the end of the corridor of Fire Bars
 * Next to the second Fire Bar on the ceiling in the bigger room
 * Before Fake Bowser, at the end of the room with the Hidden Blocks
 * On the lift above the Fake Bowser

Enemies

 * Fire Bars
 * Lava Bubbles
 * Fake Bowser

Level statistics

 * Power-ups: 1 (Super Mushroom or Fire Flower)
 * 1-Up Mushrooms: 0
 * Secret areas: 0

Mondo 6-4 (Super Mario Bros.)