If you're not going into the World Cup, I'd recommend taking those days to train some skills if you're not picked for a World Cup Game. Your energy comes right back the next day.
Ska Hymn, Stormfield, Momentum, and Presumed Dead (for obvious reasons) are the most annoying to perfect for me.
Stormfield the most so since just... just look at its chart.
Ska Hymn and Momentum are cuz I'm kinda bad at repetitive notes, Presumed Dead for the double note thing ending.
This is probably the only puzzle game I've ever completed. I was surprised with how complex it got near the end. The twisty puzzles were probably harder than the end ones, minus the last two levels in my opinion.
OK that beer bottle on the second streetlight is probably the worst thing ever. Haven't even gotten to the third streetlight yet because my guy just keeps LITERALLY GRAVITATING to the beer bottle.
This game's actually got the best gameplay of them all in my opinion. The timing's much more loose and flexible. With SCGMD4 you've gotta be real precise with the notes you hit but this one you can have some delay and/or be a bit early with em and I like that.
Of course this makes it a bit easier, but at the same time more fun since you can hit stuff you wouldn't normally be able to on other games as consistently as you can here.
 "New Star Soccer"){kind=icon}
 "SCGMD4"){kind=icon}
 "Unpuzzle"){kind=icon}
 "Tangerine Tycoon"){kind=icon}
 "Dead Drunk 1.3"){kind=icon}
 "Let's Go Jaywalking"){kind=icon}
 "Hex color idle"){kind=icon}
 "Mutilate-a-Doll 2"){kind=icon}
 "Super Crazy Guitar Maniac Deluxe 3"){kind=icon}