I appreciate you playing and your insightful comments. The upgrade menu and orbiting fragment flow in the prior build were unclear, but you weren't missing anything.
I submitted a new version that should make the Upgrade button and results screen more accessible. To ensure the basic loop functions before requiring upgrades, I also modified the dust/fragment behavior.
Breaking dust, feeding bits into the planet's core, gaining linked mass, and then using the results screen to proceed or upgrade is the desired loop.
I'd like to hear whether the first few rounds feel clearer now that you've had a chance to play the new build.