With Mystic Mines zone its too obvious that its recycled art, that might just be a personal thing though. But again it doesn't live up to the standard of the other zones.
As for Bridge zone, I would love to see an improved version of all the old master system Sonic's, but used as an extra tacked onto another game isn't the way I would like to see it done.
If I was to add these two in the game, they would be almost completely remastered to fit the style, the same goes for bridge zone. I was more thinking of if I should give them another chance...which at this point, looks like a no
Edit: forgot it was a remake, not a hack. So yeah, it's possible.
The giant enemy's work like so. Instead of going to the end of the level and hitting the sign post like in a typical game, you instead look for the giant badnik. Once you are near him, music starts playing similar to a boss and you have 8 hits to kill him. They do what their smaller counterparts would do and generally, they're fairly easy. Looking for them is half the battle.
For the ratio issue, I will most likely release two versions of the same game with ratio differences.
If everyone wants this? I sure can make a "Sonic 1, 2 and 3" bonus art style mode? If any bonus characters would be put in, Nack is the likely candidate. If another was, I'd probably but in Silver...ok I lied, I would most likely put in Metal Sonic
I have always liked the HUD, but if the majority does not, I can change it. The title screen I do kind of like, so it's most likely staying (again, unless no one likes it :P), and the sign posts were going to be something I was going to touch up near the end.