[BUG] Stardroid Chapter is broken if you're Time Traveling

[Gothic]

When you use time traveling to replay the MM10 chapter and then the MMV chapter, if you quit or finish the first Stardroid level, the game takes you to the Terra boss battle instead of keeping your progress.

Also, why can't you travel directly to the MMV chapter?

[NES Boy]

This is because the MMV chapter keeps track of more than the standard mm8bdm_saveprogress CVAR. These are the most important CVARs:

mm8bdm_mmvsaveprogress: This is the initial progression CVAR for the MMV chapter. It keeps track of which Stardroid you've defeated in an 8-bit variable. The order is +1: Mercury, +2: Venus, +4: Mars, +8: Jupiter, +16: Saturn, +32: Uranus, +64: Pluto, +128: Neptune. Any combination of four defeated Stardroids results in the small event where Dr. Cossack tells you what the Stardroids were doing in the planetary outposts. All eight Stardroids being set to defeated triggers the Terra event, after which the mm8bdm_saveprogress CVAR takes over the main progress tracking for the MMV chapter.
mm8bdm_mmvweapons: These are the weapons you get from defeating the Stardroids. Like mm8bdm_mmvsaveprogress, it's an 8-bit variable.
mm8bdm_mmvlastlocation: This is a value that sets which stage you've last played, as reflected by the planet outside the spaceship. Value 0 is nothing, values 1-8 are the planets you visit to fight the Stardroids, values 9-13 are the Wily Star stages, and value 14 is the final stage.
mm8bdm_screwcount: This is the number of screws you currently have.
mm8bdm_mm1weapons, mm8bdm_mm2weapons, mm8bdm_mm3weapons, mm8bdm_mm4weapons, mm8bdm_mm5weapons, mm8bdm_mm6weapons, mm8bdm_mm7weapons, mm8bdm_mm8weapons, mm8bdm_mmbweapons, mm8bdm_mm9weapons, and mm8bdm_mm10weapons: These are the weapons you buy from the shop, each one an 8-bit variable.
mm8bdm_rushsearch: This is the Rush Search item. Value 0 is nothing, value 1 is the standard version, value 2 is the first upgrade, and value 3 is the infinite use version.
mm8bdm_templeprogress: This is the main progression CVAR for the temple sidequest. Value 0 is the initial setting, value 1 is set after speaking to Pharaoh Man the first time, value 2 is set upon speaking to Pharaoh Man after you've bought the Rush Search and upgraded it to be used in earlier chapters, value 3 is set upon talking to Pharaoh Man after all the artifacts have been collected, value 4 is set once the teleporter to the ruins becomes active, value 5 is set after you open the gateway to the temple, and value 6 is set upon completing the sidequest.
mm8bdm_artifactprogress: This CVAR is an 8-bit variable that keeps track of the artifacts you collect during the temple sidequest.
mm8bdm_miscweapons: This is a 7-bit variable keeping track of the Mega Ball, Spark Chase, Mirror Buster, Screw Crusher, Ballade Cracker, Sakugarne, and Dawn Breaker.

This is why Magic Man doesn't actually offer to take you to back to the beginning of Chapter 13, and instead appears on Dr. Cossack's ship with an offer to erase your progress in the MMV chapter. If you just want to replay the MMV chapter without actually losing your weapons and such, then simply enter the following into the console:

map map02; mm8bdm_saveprogress 1121; mm8bdm_magicsaveprogress 1126; mm8bdm_mmvsaveprogress 0; mm8bdm_wilygolemunlock 4

Note that when returning to the present from this point forward, the state of mm8bdm_mmvsaveprogress will have no effect on anything.

[Gothic]

Oh, I was expecting that there would be a way to start the Stardroid chapter with your whole gear, but apparently you need to start fresh to do a true reset.