This ending is fairly simple to achieve. All you need to do is complete the game normally on any difficulty except Insanity Shuffle.

NOTE: If you are playing on Mibibli difficulty you may find an NPC next to a hole that mentions something along the lines of you needing to be a true hero to go down a certain path. If you jump down the hole you will be given an opportunity to do two bonus stages that are labeled as "????". Do not do both of these stages otherwise you will be unable to get this ending anymore. The "????" stage in the first hub area does not count as one of the bonus stages.

This ending is also fairly simple to achieve, albeit tougher than the previous. To get this ending you must play through the game on Mibibli difficulty. At a certain point you'll reach an area where an NPC mentions something along the lines of you needing to be a true hero in order to go down a certain path. The NPC will be standing next to a hole which will take you to a bonus hub area with two stages labeled as "????". Complete both of these stages and then complete the game normally to get this ending.

This ending is probably the most straightforward out of all of them, however, it's also probably the most difficult. To get this ending you must complete the game normally on Insanity Shuffle difficulty. That's it.

This is where the endings start getting a bit vague on how to achieve them. In order to get this ending you'll need to follow a specific set of instructions. These instructions are told to you through two different NPC's that are hidden in the hub areas. The location of one of them is fairly obvious and nearly impossible to miss while the location of the other one is hidden. Once you've found both NPC's you should have all that you need to follow the instructions which will put you through a bonus stage. Complete the bonus stage to get the ending. The difficulty you play on shouldn't matter, though I'd recommend playing on Mibibli just to be safe. You might also need to have beaten the game at least once.

If you just straight up want the instructions and can't be bothered to find the NPC's then here they are: While at the title screen, enter the following sequence of arrow keys: Up Down Down Left Right Up Left Right Down Down Right Up Left Right Down Up Down Up.

This ending requires a lot of prep-work to get and is permanently missable if you miss one certain thing. In order to get this ending there are five special items that you need to find and collect throughout the game.

The First Item
In the first hub area you normally only need to complete three of the four stages given to you in order to progress further through the game. To get the item you must complete all four stages in the first hub area.

The Second Item
In the "Cave" level in the first hub area, at a certain point you may notice a very large glass floor covering some stairs leading to a tunnel. Under normal circumstances you cannot completely destroy this floor with your attacks as they do not fall down far enough before disppearing in order to completely destroy al the glass blocks. In order to destroy them you'll need to backtrack to the left and get back in that vehicle that you hopefully used to get this far that is now probably stuck in a ditch. Fire the vehicle's energy blast, immediately exit the vehicle and run alongside the energy blast. The energy blast will reach the glass blocks and completely destroy them, allowing you to access a tunnel. Go through the tunnel and you'll be presented with a bonus stage. Complete the bonus stage to get the item.

The Third Item
This item is permanently missable. This item is found in an area where you essentially are playing with sliding ice physics instead of normal controls. (If you push to go in a direction, you continue going in that direction until you hit a wall.) Once you get far enough into the area you will probably notice the item as it's fairly obvious to spot as well as a way to continue onwards. DO NOT contninue onwards until you get the item, otherwise you will miss it forever and be unable to get it again.

NOTE: If you are playing on speedrun mode then this area will be completely skipped and you won't be given an opportunity to get this item. If you want to get it make sure to exit the game and switch to regular mode after finishing your fourth stage in the first hub area.

The Fourth Item
This item can be found in the "Crystal Cars" stage of the second hub area. A few screens over after the stage starts you'll be given an opportunity to do a minigame or progress normally. Do the minigame and a path going a different way will open, leading to another room with another minigame. Like the previous room, there will be a path to progress normally (albeit a bit further ahead in the stage than normally, as a reward for completing the first minigame.) and a path going a different way that's locked until you beat the minigame. Beat the second minigame and go down the alternate path that opens. At the end of the path will be another bonus stage for you. Complete the bonus stage to get the item.

The Fifth Item
This item can be found in the "Eggs" stage of the second hub area, however, before you attempt the stage you must make sure you have a certain powerup. This powerup can be found and obtained by jumping down a dark hole in the second hub area labeled as "To Town". Before beginning the "Eggs" stage make sure the powerup you got from the town area is charged and keep it saved up, as you'll need it to get to the item. A fair ways into the "Eggs" stage you'll come across a room with a bunch of bombs in a snake-like structure with a single breakable block at the very tail end. The room contains two paths besides the one you came from. One on the floor that leads further through the level and one on the right wall that leads to a hidden area. In order to reach the path on the right wall you'll need to shoot the bomb blocks, jump on the breakable block before the bombs destroy it and quickly jump to the path on the right wall. You'll enter a hidden room with a path that is seemingly impossible to traverse, however, you can use the powerup you got from the town area in order to get through it. Once you get through it, you'll be presented with yet another bonus stage to complete. Complete the bonus stage to get the item.

Getting The Ending
Once you've finally gotten all items then you can finally get this ending. When you reach the third hub area, find a stage called "Saturday" and enter it. At a certain point through the stage you'll find all the items you've collected hovering above a spike pit. Kill yourself by jumping into the spike pit and you'll be put into one last bonus stage to complete. Simply complete this last stage to get the ending.

Traversing The Hub Areas
If you missed an item besides the third item you might need to backtrack to previous hub areas. Here's how to do so:
-Hub Area 3 to Hub Area 2 - Find the vehicle that brought you from the second hub area to the third hub area. It'll be broken down, but you can still use it to get back to the second hub area.
-Hub Area 2 to Hub Area 1 - Find the dark hole labeled "To Town" and jump down it. At the very end of the town area you'll find two portals labeled "World 1" and "World 2". Enter the one labeled "World 1".

This "ending" may just be more of a general secret than an ending, but it's still fairly noteworthy. In order to get this ending you'll need to aquire some items and do something with them like in the second secret ending, but there are less items and none of them are permanently missable. One thing to note about these items is that they will appear on Mibibli and if they get hit by any enemies or if Mibibli dies then they will disappear and you must collect them again. Also, make sure you have access to the third hub area before attempting to do this ending so you don't waste time trying to complete the entire first and second hub areas with the item still intact.

The First Item
The first item can be found in the "City" stage of the first hub area. It's in the very first screen with actual obstables in it and should be fairly obvious to spot. It's also very easy to just go and pick it up.

The Second Item
The second item is a bit harder to find but just as easy to get. In the "Monday" stage of the third hub area, if you look very closely at the top of the second screen in the stage, you'll see the item. You'll need to shoot the item in order to get it down to the ground so you can pick it up.

Getting The Ending
Once you've gotten and kept both items, make your way over to the "Water" stage of the second hub area. Once you've gotten to the midway checkpoint in the stage you may notice a small hole in the ground that's flashing a light sky blue color. Enter the hole and proceed through the areas it leads you to until you see a weird-looking NPC on a ledge. Jump onto the ledge and touch the NPC to be transported to a bonus stage. This stage goes on forever and every screen is filled with random enemies. It never actually ends but it's noteworthy enough for me for it to be in this guide.