Based on all the feedback I've received, I will share here my to-do list for this project:

Top Priority

• Splash screen
• Main menu
• Change the water generation/shader
• Reposition the camera
• Make better waterfalls
• Create a tutorial scene
• Rework the controls
• Create paddling animations for Bob in Blender
• Create new easy scene
• Split current easy, medium and hard levels into separate scenes
• Relabel scenes difficulty names

High Priority

• Make separate spiky colliders
• Shorten the game complete music sample
• Rework time gates
• Improved "life over" feedback
• Improve "level completed" feedback
• Change fire barrels to bombs/TNT barrels

Lower Priority

• Add a mini-map
• Rebalance scuff damage
• Add a world/progress map
• Add a continue function
• Add bouncy world-edge colliders
• Improved graphics

Consider These

• Work out number of levels required (Easy, Medium and Hard, possibly Bonus rounds)
• Treasure boxes
• End of Level Scoring
• Global Scoreboard