I have a few suggestion; one for balance and the others visual tweaks.
For balance, I think the player should be given full shields on continue. If a player struggled with 8 HP, having to try again with 2 ain't gonna help much.
As for visuals, could you get rid of the screen shaking when you're shields are gone? At best it's a distraction, and at worst it makes tracking enemies harder.
Lastly, I think the status bar could use a little tweaking. The way the meters are segmented appears as if your shields and blast max out at 6 units when they always increment/decrement by 2, meaning you actually have 3. And as for upgrades, you only need 2 capsules for one, so you hardly need a meter for it at all, probably an icon should've sufficed?
And for picking up the shield cap upgrade, it might be better to visualize this with a larger meter rather than an ×1/×2. If you move the blast meter and shorten the upgrade meter, (since it doesn't need to be as big as it is), you should have enough space to show it like this.
Note how 7 units are shown here, since the cap upgrade as it's currently displayed shows an empty meter with an ×2. With this layout, 5 units would be rendered as 5 blue squares, and we'd still have 8 hits total clearly visualized.
Already I've seen an exciting game with the progression through the solar system being reminiscent of Konami's Gyrus! And thanks for reading!