I'll chime in because I analyzed this game myself one day and I want to get out some more details. Note that I use the non-CM version for my pointer references.
- There is no RNG whatsoever for the enemies (three different movement types), the cars or the powerup spawning orders or timers. I'll break down the lists I found for each one:
- The enemy ID spawn list at $80AA55 (which has timers and object IDs attached together) loops after 30 enemies.
- The enemy X coordinate spawn list at $80AA42 loops after 18 enemies.
- Cars, which spawn in as the 14th and 30th enemies, have their own Y spawning coordinate index. The list, stored at $80AA2E, loops after nine cars, but it's just 3 entries duplicated 3 times.
- Powerup drop lists, stored at $80AF2F are handled on a per-kill basis, and loop after 40 kills. The invincibility powerup (which renders you invincible for 480 frames, or 8 seconds to NTSC standards) spawns upon the 16th and 31st kills. Death "powerups" are more common, spawning upon the 2nd, 10th, 11th, 17th, 19th, 22nd, 30th, 31st, 37th and 39th kills.
- The boss spawns after 30 kills and it is the only interruption to the regular gameflow.
The argument that I have for the TAS is taking out the boss, though the game continues after this. But the argument that I have against this... is everything, and I mean everything, being a fixed list. The spawn and timer lists effectively reset after 90 enemies (the least common denominator of the three combined), and the only other difference is the powerup drop list, which runs on a per-kill basis and not a per-spawn basis. Thus, going through 90 enemies and at least one boss, even without accounting for the powerup drop list, would exhaust all unique content (assuming nothing else can be found).
And yes, the music does eventually stop... but it's caused by a combination of the phrase data stopping the song instead of looping it and a bug in the music data. The entire song is two notes of 35,712 tempo ticks. The music data has a bug in it that causes the second note to be silent. The tempo is set to the slowest value possible, for 1, and it uses the original source N-SPC variant, as I documented
here on the SNESLab wiki. I estimate that it would take five hours and four minutes before it would stop playing.