[General]
Source? Tags?
Consider using custom combo colours.
Consider adding an easier difficulty.
Keep the blacken storyboard element to the end; right now the background flashes suddenly again. Maybe also change the background colour to black, just for the loading screen.
I thought that hitsounds as a whole were too loud.
Consider silencing the sliders (the sounds when you hold a slider down, not the ticks or sounds when hit/repeat) during the softer sections. It's particularly noticeable in some places, like 03:20:013 (4) on Metroid Mix.
[Normal]
00:42:080 (1) - This section was too loud, covered up the lyrics.
01:02:014 - Excess timing section(s).
01:21:064 - Add a note? I kept hitting this instead of the 1.
02:58:014 (2,3) - I thought these could be positioned to look nicer.
03:11:014 (4,5) - Consider replacing these with a single slider. (maybe just delete 4 and move 5 in its place)
03:28:014 (3,4,5) - Whistles seem to be much louder than the other hitsounds; dull these down a bit?
[Metroid Mix]
00:37:063 (3,4,5,6) - Geometry police says that 3-4 and 4-5 look different.
00:45:029 (8) - Sliderticks sound pretty bad on this slider..
01:11:063 (5) - Move this back 1/4?
01:45:063 (1) - I liked it a bit more without the clap.
02:18:046 (9) - Remove note?
02:32:046 (1,2,3,4) - Not the best diamond.
02:48:079 (3) - Symmetry with 1?
[Hard]
00:42:080 (1) - Too loud again.
01:45:064 (1) - I thought this sounded a bit better without the whistle.
03:29:047 (3) - Add a finish?
Nice. Star~