I made an update to the game, and here is the list of changes.

• Double tapping left/right to dash can now be toggled on or off. It defaults to ON for previous players and OFF for new players.
• A Mac version has been added.
• The text for the dash powerup now mentions the dash key set in the control settings.
• Invulnerability time has been reduced for all enemies, including bosses.
• The first boss has 2 less health, a slightly lower starting speed, but a much higher max speed.
• A save point has been added near the first powerup.
• The main music loop has been extended and the final boss music has been changed.