Mortal Kombat: Piano and drums don't really fit well by themselves. The guitar came in later, but it's still pretty empty. Even with the guitar, it's lacking on the bass end. Oh, and the lack of secondary parts and a decent melody hinders it as well. The drums are very repetitive too...
Jaan-E-Mann: Weird... again, piano and drums... ? The other thing comes in, which I assume is suppoced to be vocals, but it just matches the piano. VERY lacking on the bass end, and EVERYTHING is repetitive. At least it's kind of catchy this time though, and a little dissinent, which is mature for a composition, although I think in this case that was purely coincidental.
Rock And Roll: I assume this is supposed to be a guitar solo, but even if not, this needs a lot of work.
OVERALL
- Vary the drums more
- Add something like a bass guitar
- Create secondary parts, whether it be faster moving parts, or slower drawn out parts.
- Harmony ~ There is almost none.
- Vary the everything more
- Choose a key signature; you aren't experienced enough to write in modes yet. Best to start out in C Major (No flats and sharps), it's the easiest key to write in.
You did better than I expected, and you show potential in my opinion, still needs more work. This is the first I've heard from you, so I don't know how much you've improved before, or if this is your first. Keep working on it, you'll get there. (I've definately heard worse)