You have chosen your samples wisely. However, you tend to start slow and depend too much on building your beat up. Also, develop your variations more. Listening to the same eight or so notes over and over can get quite tiring. I recommend you check out the works of Yuzo Koshiro of Streets of Rage fame. Also, look up an ost for the Genesis game Verytex. Take note on how their tracks tend to repeat a series of notes throughout, but they spice it up to keep us hooked.