Just a quick response - less time than I'd hoped for, unfortunately!
Regarding palette swaps: I'm not against these at all - I have a few in place right now, but they mainly consist of 'restored' enemy units, such as the 'purple Dark Dwarf', 'purple Goblin', 'orange Lizardman' sprites. I kind of justify it as Sega were perhaps intending to use these as enemies but ran out of time or memory, so why not build off of their foundation. Typically, if I'm looking to add a brand new enemy, they will include a brand spanking new set of battle sprites, map sprites and if necessary a unique portrait. Happy to perform the necessary palette swaps for anyone who needs a hand, but LIL looks like he's got ya covered.
- Manticore: It's on the to-do list. Woo-hoo!
- Hippogriff: Looks pretty cool and also a creature I wasn't previously familiar with. Perhaps a little too similar to the wyvern or chimaera, so not sure about this one...
- Druid: Dan designed something similar a year or so ago, although we called it the 'Dark Disciple':
- Leviathan: Very high on the to-do list!
- Fenrir: Also on the to-do list. My goal is to give this fella a nice big battle sprite to reflect the Nordic mythos
- Fafnir: I'm interested... sounds exotic!
- Banshee: I likey! Might add this one to the list.
- Spectre: Me and Dan planned a similar enemy in 2016, only we called it the 'Wraith'; he's due for a big overhaul but here's how he ended up back then:
- Gremlin: Could utilise the unfinished purple Goblin palette swap. I used to refer to this iteration as the 'Imp' but since he sports similar colours to the Ghoul, I had him appear during the Shade Abbey battle.
- Vampire: Yes, yes, yes! I'm rally surprised that aside from Lemon in SF2, there exists no vampire enemies to fight in the early series (maybe they appeared in later games, but I haven't played beyond SF3). I have the Vampire higher on my to-do list as a playable character, but there's always room for more enemies!
- Kraken: They did this enemy so well in SF2, that I don't think I could do it justice in SF1, especially given the current limitations of map sprite sizing. Also, I had completely forgotten that a Kraken appears in RoDD! I've completed that game twice and I really can't recall where the Force fights him... hmm. Although, after checking his sprites on spriters-resource, it seems that he really does exist and my memory just isn't on its A-game today!
- Ogre: This was a very early project for me and Dan, and looking at it now I feel that there are many areas that could be improved upon, but here be he:
- Troll: Now this was another early project which I still to this day really like - the result was pretty much spot-on and Dan really nailed it. Here be the (two-headed) Troll:
Let me know which of RS's suggestions you like the most and I'll run them further up the to-do list.