(Sorry for my English) Tips for killing last 4 yellow orbs: select 1 orb, shoot and follow it. When you lose sight of it, fly in the opposite direction until you meet it again. Repeat until it is destroyed. The main complexity is finding damaged orb after you lose it.
Workarounds for glitches. If keyboard doesn't work (but mouse works), click outside the game window, then click in game window. If drag-and-drop doesn't work, press Shift (I pressed both, not sure if one is enough).
Tried latest Firefox (different profile). Game progress wasn't saved at first time but saved at second time (no settings changed, just reloaded the game). Strange.
For me, problem with saving progress was caused by damaged Firefox profile (I downgraded my Firefox): https://bugzilla.mozilla.org/show_bug.cgi?id=1357428
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