It plays alright, but there's not much to it. The idea of keeping yourself stocked up against a ticking clock is a fun idea, and I can think of several ways it could be very tense and exhilarating.
Most of what I can offer is little things. I feel like the ticking clock would play better if the there was an emphasis on speed in movement, making it a more manic dash between pickups and timing the jumping puzzles. Aside from that it's mostly nitpicks. Jumping feels very floaty, and I found it kind of annoying that holding the jump button automatically double jumped all at once. Additionally, the jump noise is a little grating.
Past that, It's a pretty solid core, and it's ripe for additional building!