Mighty Bomb Jack/Stage 4

All of a sudden you go from straightforward, single segment stages to one of the most complicated stages in the game. Stage 4 not only features multiple segments, the segments branch, forming two different pathways through the stage. The lower path is considerably easier than the higher path, but the higher path features a warp and more treasure. More importantly, the higher path contains the first secret coin in the American version.

Segment 1
The branching starts right away. At the right end of this level are two exits, one to the right, and one up above. If you take the lower exit, continue on to the next Segment. If you take the upper exit, jump down to Segment 3.

Segment 2
The lower path is the easier of the two paths, and it contains a number of secret chests. There is a secret treasure room in the middle, but jumping in can be a dangerous temptation, as the room below it is the only torture room that you can enter voluntarily. Once there, you'll have to jump off the ground 50 times in order to escape. Once you reach the far right exit of this segment, you'll arrive at the bottom of the last segment.

Segment 3
This segment of stage 4 is a vertical climb. The exit to the next segment is shortly before the very top. Before you pass through it, it's worth exploring the very top for an extra life.

Warp to Stage 7
If you're going to attempt the warp from stage 4 to stage 7, you'll need to meet a few preconditions. First, you must collect the Sphinx that opens the door at the very top of the segment. The Sphinx is located directly beneath the hidden slave at point H. In the Japanese version, you must jump several move times to make the brick beneath the Slave disappear. Once you collect the Sphinx, you can enter the door at the top. When you pass through it, remember to push left as you regain control of Jack, or you will simply pass back through the door and lose the opportunity to warp. In order to successfully activate the warp, you must 1) have no Mighty Coins in your inventory, 2) wait at the far left side of the warp room until the Timer reaches 1, and 3) be pushing on the control pad when the Timer is about to switch from 1 to 0.  If you do all of this successfully, the timer will suddenly switch back to 60, and a door will open in the left corner of the ceiling.  Passing through the door will send you to the third segment of Stage 7.  Note that you will not be able to collect the first Crystal Ball as a result of warping to this location.  Since you are likely to have to wait out a long time for the Timer to reach 1, it helps if you situate yourself on the left side of the room such that the mummies transform into Hanezos or the the fireball Desufas which bounce off the treasure chests and leave Jack alone while you wait out the timer. Remember that the number of times you press determines which enemy the mummies transform into. To ensure that you are pressing right when the timer becomes 0, jump into the air and tap A as you push right into the wall floating in mid-air. If you push right too late, you will die due to "time over". In general, this warp is more trouble than it's worth.