Looks good at first glance!
I think I'd be checking the rules a lot while playing, just to make sure I was rolling the right die, and achieving success on the right number.
Did I read correctly that a spellcaster has a minimum chance of 1/3 to take 1 damage when casting spells?
Ranges
Melee - Toe to toe
Close - Across the room
Medium - Across the street
Long - Down the block
Areas
Target - 1 object or subject
Small - a table
Medium - a room
Large - a house
I quite like it, though you are stretching the definition of "D20 game" with all those d6 rolls.On the first read, my only worry is that the Heroic Feat resolution might be over-used. I'm guessing that you really mean heroic and feats such as climbing a wall with a rope wouldn't need a die roll. That's great! But a sentence or two to spell that out would be a kindness to new players or those coming in from rules-heavy games.