Starting at the Chasm section of Forsaken City, jump and dash to the platform directly above you, then trigger the conveyor-belt platform that allows you to exit via the top left of the screen.

In the next room, use the conveyor-belt platform to propel you upwards towards the exit. You will surface with a conveyor-belt platform directly above you which, when activated, is shown to be blocking a secret screen.

Once on this screen, the route to the B-side should be quite clear. Watch your timing to platform between the pink and blue alternating platforms across the bottom of the screen up to the pink block in the top left, before using the conveyor-belt platform and a well-timed dash to propel you to the B-Side.

Starting at the campsite at the beginning of the chapter, exit to the right and continue to the bottom right exit of the next screen. Fall down the hole directly to the right of you and fall all the way to the floor of the next screen.

You should notice the brick wall to the right is a little worn and a dash will send you through it. The next section is quite linear — just progress through until you once again find yourself in the room with the wall you just dashed through. Dash through the dream block on the floor to find this stage's B-side room.

This B-side is also quite simple and mostly requires you to watch your timing. Make your way across the alternating platforms and dash through the dream blocks in order to claim this level's B-Side.

Starting at the Elevator Shaft in Celestial Resort, head up and then left. Keep progressing left until you reach the key needed to access the room Mr. Oshiro is desperate for you to stay in.

Once you reach the key, there will be a damaged section of the wall to the left, which will take you to Celestial Resort's B-Side.

Dash up to the blue alternating block, timing it so that you can pass through the block and land just as it turns solid. Next, jump between the nearest pink block to the blue one before landing on the small pink block above you.

You now want to time a dash so that you pass through the pink block to your left just as it turns translucent and grab onto the wall covered with water. Drop onto the pink block below you (once it's solid) and jump up to claim your prize.

Starting at the beginning of Golden Ridge, progress right as normal. You'll eventually come across the Old Woman, but just keep progressing to the right as you normally would through the level.

Eventually, you'll come across a relatively open section with three white clouds ascending to the top right of the screen. Fight your instincts here and jump off the second cloud towards the top left of the screen, using the wind and a dash to your advantage. Exit the next room to the left.

This requires some more precise platforming. There's a pair of skull binoculars above you that show that the B-Side is located directly to your left. You will need to platform between (and through) the alternating blocks to reach it.

For the simplest route to the B-side, start at the Depths and head out the door to your right (the switch is located above the mirror) before taking the upward path through the narrow corridor.

In the next room, find a vertically moving platform to the right to reach the exit in the top right of the room. In the next room, you'll need to maneuver your way around a dashing platform.

Once in the next room, head down until you see a red orb, which you can use to exit this room directly to the right. The next room contains a switch in the top right-hand corner and the door directly below it on the floor.

Hitting the switch above you in the center of the next room can be a little finicky, but once you've opened the door you can exit through it to the right to find yourself in a room with a weakened bit of wall at the end. Dash through it to reach the B-Side.

Starting at Hollows, head up and left towards the Angry Platform, which you can use to smash the semi-smashable wall below.

Once next to the feather on your right, there's a secret path behind another semi-smashable wall on your left. Use the same Angry Platform to smash through this.

In order to reach this B-side to the far left, you'll need to be sparing with your dash and make use of the gems in order to replenish your dash mid-air.

Starting at 1500M of your final ascent to the summit, progress through the Celestial Resort as normal until reaching a small room with the exit blocked by a shield platform (the kind that sounds like a doorbell when activated).

Once you've cleared this room, you'll spot the entrance to the B-Side screen at the top of the next stage. After jumping over the ledge, up to the tall platform, the B-Side will be located through a hole in the ceiling to your left.

The most challenging obstacle here is a Z-shaped platform that requires the tricky maneuver of grabbing onto one side until the block goes transparent, then dodging up through the platform to land on it once it goes solid again. Clear this and you're home free.

In order to access the core, you'll need to have beaten the game, as well as collected the four Crystal Hearts. The B-side can be found in the climactic final section of this level, in the Heart Of The Mountain.

As you work your way up the core, evading the rising lava, you'll eventually come to a dead end. At this point, the only way to progress is through a secret destructible wall to the right leading to what is, rather fittingly, the most challenging platforming sequence of the whole game. Succeed, and the B-Side is yours.