Formatting: good.
Use of illustrations: nice!
Table of contents: proper.
Writing of rules:
This seems to be where Nexus needs the most work. A lot of the rules actually have the feel of, "hey, here are several cool things you can do." Here's an example of my personal confusion-
"Knockback
If you take enough damage that without armor you would have taken heavy damage or better then you take
knockback. You get knocked back a few yards. If you take more than what would have killed you will be knocked back
several yards. If you take a melee attack from a creature with a strength bonus 3 greater than yours then you go back a
yard for every point greater than yours + 3."
First, I'm not sure if this applies when I'm wearing armor or not wearing armor. Next, what's "better" than heavy damage, heavier damage, or lighter damage? How many yards is a few yards? Is several more than a few? Why doesn't this apply to ranged attacks? What if I'm much bigger than the creature knocking me back? Do I go back a yard for each opponent strength point over mine +3 yards, or for each opponent strength point over my strength+3?
I'm not a rules writing expert. However, I'd like to recommend that for each rule, you decide:
1) The precise intent of the rule.
2) How that rule interacts with every other rule.
3) What is the most concise explanation of these first two considerations.