Last night I thought I had (for the first time) mastered the ship completely.... when - just before the exit room - I looked at the map and realised....I had again missed an entire section, albeit one I knew already and always visited in earlier games. It's the section below and around the twisted ladder, where my and most other people's cabins are.
I checked again.... and found the reason was.... apparently I'm missing
one purple key. That happens usually around the time I'm in front of Freddy's cabin.... so I can take the purple key above the many colored doors that lead to Freddy's and then decide whether I continue straight ahead into his cabin (which doesn't lead to much - beside a little backpack money).... or if I take the purple key and go back up and visit the
bar w/ dancefloor
room. Only the latter allows me to finally go to the
twisted ladder section
.
There at least..... after much searching.... I finally found the way back (hilarious....amazing work, brell!!) into the
first cabin section
. But I never find the one purple key missing to enter Freddy's cabin.

>
(But that way I can at least finish w/ only 1 room left unvisited.....) 8-)