NOTE: This ONLY works if the graphics are set to New! Soon, this will become a pack of Sonic characters. If you want to play with the Original Cave Story characters, just switch the Original.
Yes, the second screen shot shows the Cave Story Doctor, but just covered in black. I couldn't find any sprites that would fit in-game, but it's only in the title screen. I tried looking for him in an Eggmobile, but those sprites were too big. And yes, this is legal as long as I credit the people who made the sprites.
Also, if anyone would want me to create more characters to add, I'll do my best. Both Sonic & Tails are on the way BTW.
Anyway, this mod allows you to have the Doctor replaced by Dr. Eggman.
IMPORTANT: Make a backup file of Cave Story itself before you download this, because this mod will replace any .bit file that is needed to have Eggy in it.
UPDATE: Added red eyes to him when he has the Red Crystal's (Or Chaos Emerald) power.
UPDATE 2: You can now see the Doctor as Eggman in Curly's story. Originally, if you played Curly's story, you will see the Doctor as himself until he had the Red Crystal's power within him, thus turning him into Dr. Eggman.