Very well done platformer! There is quite a bunch of mechanics already and I can see the speedrunning/high-score routing potential.

The pixel art is pretty well done and the player sprite is really cute. The music is also pretty cool. The death and finish animations are also nice.

Some ideas for improvement:

• break up the complete silence during the start with some letter sound effects
• the music randomly goes slow and fast, it would be super cool if it was synced with the timer's tempo
• the timer tempo could be a bit clearer, see above for an idea how or increase the font size more with rising speed
• a short on screen control tutorial would be nice (shift to pick up etc)