i made this mod with the issac character editor and had this idea, so I made it and it didn't come out so well. The items he starts with are:
Soy Milk
Moms Knife
Thin Odd Mushroom
My Shadow
Ventricle Razor
Black Feather
Betrayal
And that's it, this character replaces issac. Have fun!
For rebirth, this character has less items.
For Afterbirth+, put the "gfx" and "players" into the resources as it is not a seperate character. Let me know if it works for ab+.
Please report any bugs in the comments.