After receiving feedback, I made some changes and added a new mode.

Changes in v 1.1:

• Added a "speedrun mode"
• Disappearing platforms now have a lower opacity when disabled
• Disappearing platforms now stay disabled for 1 second instead of 5
• Camera movement is now based on player velocity instead of input
• Player is now less "slippery" while on the ground
• Increased control in the air
• Removed "sound effects" volume slider
• Fixed minor bugs