Here's mostly everything that changed in Update #1 (0.1.0):

• Added 3-4p mode (2v2 and 1v2)
• Added controller support for 4 players
• Added rudimentary keyboard bindings for all 4 players
• Added two new levels
• Added "boomerang ball" option
• Players run slightly faster when charging
• Linux version is now downloadable (I reserve the right to support this version poorly as I have no proper means to test it)
• Bugfixes
  • Fixed visual and collision detection issues in levels
  • Balls no longer randomly roll to another player's side when starting a round
  • Improved aspect ratio support
  • The in-game score counter wasn't always visible while playing
  • Various other menu & hud fixes and improvements
  • Many other bugfixes

Here's stuff that changed in Update #2 (0.2.x)

• Added new kick targeting controls
• Added new wall jump ability
• Added a new arena
• Added new target practice mode with several challenges!
• Removed game launcher
• Added new menus
• Added improved graphics and sound settings to menus
• Lots of visual improvements
• Some new gameplay mechanics and other improvements

Here's what changed in Update #3 (0.3.0)

https://steamcommunity.com/app/1352130/discussions/0/3008927444662278846/

Here's what was added/changed in Update #4 (0.4.0)

https://steamcommunity.com/app/1352130/discussions/0/2998800559161799005/

Changelist for Update #5 (0.5.0-0.5.1)

https://steamcommunity.com/app/1352130/discussions/0/3149682775497950048/

Changelist for Update #6

- Menu overhaul

I basically revised most, if not all of the main and in-game menus. Nonsense looks a lot prettier and is intuitive now, at least I think so! :)

The team select screen is still a bit work in progress and some of the menu transitions are a bit annoying (like when you return from the game, most of the player-made settings reset). I'll get around to fixing them as soon as I can :)

I've been pretty busy with work stuff so no gameplay changes in this update, but I've scheduled some improvements and new features for the next one. Stay tuned!