Main Menu: Groovy! Love the organ sound. Gives me beach vibes.
Lousy Ol Town: Compositionally this makes such a great town theme. I'm trying to place what game it reminds me of (might just be Crash like everyone else lol). Nice percussion!
Onward: Love the intro melody, especially coupled with the time signature I find it pretty memorable. The chromatic bass movement upwards at 0:20 is so cool. Rhythm got me moving! It's got the feel of some of the more rhythm heavy tracks from Trials of Mana. I second what Troisnyx said, I feel like if the chords in the back were broken up a bit more, it would add to the rhythm even more!
Oh I forgot the bonus oops (edit incoming)
BONUS: You Lost: This is in fact a much darker tone so I can understand leaving it out. This is really cool though. Love the bass sound and that higher synth a lot. In a more extended OST if it were a real game, I could see this fitting in somewhere especially late game. Or as a game over theme like the name suggests.
Nice work!