Well some games probably use sequences, others probably use streams.
I mean, take Super Mario 3D Land's "Beat Block" theme (or whatever the heck it's called)... I swear almost EVERY time you enter the level, the tune plays differently. It has the basic drum beat, and 'beep' sounds that are always playing, but then it has those odd patterns, which play in a random order, and as I said, so random, that the order can be different every time you play it. Now that to me, sounds sequenced.
It's actually sound effects playing at random, as if you use the P-Wing, no music plays. However, the beat only plays if you use a Star, but the music does not stop when the SMG2 Teleporter theme is playing in that game, and it doesn't seem to reverb like most other songs, so I'm suggesting that's sequenced too. I'm also suggesting the Star and Athletic themes are sequenced too, as I don't hear any reverb on them, but I hear them with the P-Wing.
I'm also suggesting this game uses streams because it plays an exact replica of the SMG2 Cosmic Clone theme.
Maybe most of the tracks are sequenced, but we won't know unless we hack the game. Which, for the squillionth time, probably won't happen anytime soon.
Also, I didn't mean that it was orchestrated. I know it isn't. But I hear samples I never hear in a sequenced track that isn't streamed into the game.