This is already fantastic. It's a far cry from what I loved about the original, and aside from my comment on Newgrounds I don't think I've told you how much I love the original. The original haunted lands was nails hard in a really classic, and good way. Jumping had to be precise, combat was nail biting and not in a trial and error way of difficulty. There was a beautiful simplicity to everything. I must have tried it a hundred times now and I still haven't beaten it (just got to the sewer section last week)
Some changes I find odd, like reloading while moving which in the original haunted lands added a ton of tension, but I get that it's a player convenience thing.
Haven't played a ton yet, but it's nice. There is a LOT more variety and complexity in this version, which surprised me. Curious to see where this goes. It looks like it already has a ton of content. The original felt like a love letter to the games that inspired it, and an attempt to fuse all of them, doom, Bio Menace, Commander Keen, Duke Nukem 1&2 etc. I only have less than an hour in right now, but This feels a little more like an attempt at a more "modern indie game" take on the same ideas.
If you ever do a full paid release, and you should, this is awesome, see if you can include the original haunted lands as a bonus. Maybe as a "Retro" version.