Got the throwing knives in La Mulana. Chain whip is too much of a pain in the ass to get so I'm gonna skip it. Oh, also got the grapple gloves. Anyway, no where to really go in the inferno at this point. I get a lot of hints telling me to go to the /back/ areas, except I need more MSX roms before I can do that (the manual indicates which ones those are -- I don't have them). Eternal corridor is a no-go. So I have one other place I can really explore, and it's weird. Otherwise, I have two bosses I could take on. If I can find a lantern, though, I do get a few more options. Same if I can find some more seals.
There's also an unopened chest in the giant's mausoleum but I think it's just a map and map's aren't useful.