Allright, here we go.
Random melodies
I don't know did you mean it to be so, but some of the instruments (two same instruments) that play in same time, play louder than with one same instrument alone. I don't know if I explained it clearly enough. I also don't know if this can be fixed in pure midi songs since I haven't ever done midi music.
But the song. Random melodies. Includes kind of various songs right? Pretty cool and atmospheric. When you do "simple" midi songs you have to be very good at composing and you are good in it. I don't know what to say but just that it's good!
ps. I liked the strings!

k:
Rhythmic Streams
Somehow beginning of this song reminded me of transport tycoon. :blink: I just don't know but I didn't find much from this. Basically it's okay, but it doesn't have any kind of climax (or what ever it's called). A fast ending could be cool where drummer gets wild and amazing guitar solos end the song!
River through your heart
Oh no. Sounds like one of those soft romantic songs.

But after beginning the song gets better with that electric guitar (I presume its electric guitar). Sounds like sixties. However there is one lacking thing: singing. Since you don't have singer you should have made a "singing melody". Now this is just kind of background music with mic off.

Very good composing again however.
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Im music maker myself too but Im not a superexpert and the language barrier blocks some thoughts. I hope that helps a bit. Maybe I submit some of my songs someday and you can have your revenge.
Good work!
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EDIT: Oh and one more thing. What softwares do you use more than guitar pro? Have you used any of those non-midi programs.