Version 0.4: Challenges!

An update! This will likely be the only one this game ever gets, but who knows! Anyway, without further ado, the changelog:

v0.4 Changelog:

ADDED
-New rocket launcher model and muzzle flash effect
-CHALLENGES: A new menu is available on the main menu that displays 14 different challenges to complete!

BUGS
-Fixed a bug where music would start playing at full volume if you quit to the menu and restarted
-Fixed a bug where quitting to the menu and selecting a different ball would not change the ball type
-Fixed a bug where rockets would hang around for a while after exploding