Small update tonight.  I had to work on some other things, so not much progress on this update

UPGRADE SHOP

• Added tooltips to the shop buttons.
• These tooltips give basic explanations of what the upgrades do.

KNOWN BUGS

• Game sometimes crashes when transitioning to the upgrade shop.
• Sound gets choppy right around score 7000 (no idea why just yet).
• Music isn't starting on the first time in the gameplay room.
• Sometimes a tooltip will remain after transitioning away from the upgrade shop.
• Did I miss any?  Please let me know.

FEEDBACK REQUEST

• Was the game fun?
• How can we improve?
• When you don't have a shield, should you only receive shield powerups?