The jungle theme from the NES port of Metal Gear. Original by Kazuki Muraoka.
Not only is the jungle level exclusive to the NES version, this game's soundtrack is different from the MSX version. And I don't mean that they sound different as in what happens when a song is transferred from one sound chip to another. I mean different as in the compositions are different. Only half of the songs from the MSX version are the same as in the NES version.
Aside from it being too loud (dropped the volume to w186), it was a solid port. Couple of things I'd like to point out, sample 6 and 9 (kicks) and 7 and 10 (snare) both sound almost identical if not exactly the same, why not get rid of one? The adsr for the kick could be better, try $8F $F5 (right now you have infinite sustain which sounds bad since the sample loops). I'd try playing around with some adsr for the snare as it cuts off too abrupt. While not necessarily a reason for rejection since the overall port was good for what is was (in my opinion), it still needs some work.