I've been continuing to work on some issues that you guys have been reporting, thanks again!
The changes from the experimental branch are now live in the default branch, so I've added those down below as well :)

General Fixes

• The sphere will no longer get stuck in a infinite horizontal bounce
• Locked characters, spheres and stages are now visible in the character selection screen blacked out to give an indication of how many things there are left to unlock
• Optimized animated tiles, and possible crashes caused by high memory usage when playing the stage for an extended period of time (let me know if you still run into this!)
• Fixed a bug where players 2, 3 and 4 could still select a different character and palette after confirming their character

Baphomet

• Fixed a bug where baphomet his charged move would not shoot the sphere froward when the control stick is not pointing in a direction.

Kao

• Fixed a bug where the flute would play twice when using the charged move

Fennel

• Increased uncharged dash distance
• Fixed graphical glitches caused by the dash smoke particles

Taya

• Changed 4th palette option

Stages

• The Volcano stage now spawns a rock once in a while which holds an item.
• Fixed a bug in the Squash version of the Volcano stage where the AI would not approach the sphere on his turn.
• The arena enemies in the Dungeon stage are removed when a game is complete, clearing up the stage for a rematch.

Items

• Fixed a bug where the shrink tome would incorrectly scale the sphere when used by Kao
• Changed the angles on which the shield would get damaged, making it a bit easier to destroy now

Multiplayer

• Each multiplayer session now yields 25 coins

Singleplayer

• The singleplayer campaign now has 3 difficulties; easy, normal and hard. The amount of coins scale with the difficulty you've chosen.
• The AI will now use picked up items
• There is now an indicator on your progress in the campaign
• Made several small changes to the AI (let me know if it's better!)
• Fixed a bug where the generated stages would not reset when exiting from a match via the pause menu.
• Improved AI behavior for squash mode when it's not the AI's turn

Options

• You can now set the BGM and SFX volume in the options menu
• The tutorial now has background music

Spheres

• Fixed a bug where some of the newly added spheres would not be unlocked properly
• Increased drop rate of some of the rarer spheres, making it a bit easier to collect them all
• Fixed a bug where the ghost sphere would make the menu unresponsive
• Fixed a bug where the additional spheres created by the double sphere would not be cleared when a point is scored

Localisation

Prepared all new content for localisation. I expect to receive translations just before or just after release. Until then some languages are missing translations and no text may appear, sorry!