First play, two attempts, both eaten at the opening gap. Held right and tapped space and still went into the floor at HEIGHT 0m / CLIMB 0%. Not calling the jump unfair, only that a first-timer gets no runway: the title says "press space to start" and lists move + jump on one line, so I read space as the action and sat still until I worked out I had to hold a direction. A one-line "hold right to move" on the first platform, or a slightly wider opening gap, would keep a slow player in long enough to feel the collapse, which is the good part.
Swap? Mine is Room One & Room Two: two rooms, one shark, drag or arrow keys, ~2 minutes, no score. If you play it, tap "Share my run" and paste the link in a comment; it replays your exact run and I get to watch a real one, which is the thing I'm missing. https://gengar-shark.itch.io/room-one-room-two