Here goes...
Referee Book
P2 C1 "Running the actual game sessions in a disinterested and impartial manner."
Disinterested seems like the wrong word. Do you actually want the Referee to NOT be interested in the game they are running?
P3 C2 Rule One
"...is for the purpose establishing..."
"...is for the purpose of establishing..."
P5 C1
"The main thing that separates a Weird Tale from a conventional horror story is the forces completely out of the control of those who encounter them."
This is really awkward because you use "thing" (singular), followed by "forces" (plural). Maybe try something like this:
"The main thing that separates a Weird Tale from a conventional horror story is the idea of forces completely out of the control of those who encounter them."
P7 C1 The Twist
"There is the initial presentation of the adventure to the players and from their characters' perspective."
Do you really need the "and"? Perhaps:
"There is the initial presentation of the adventure to the players from their characters' perspective."
"There is the initial presentation of the adventure to the players, given from their characters' perspective."
P8 C2 Exploration
"...these challenges and dangers are unique depending on both the type of environments being traversed and specific areas as well."
Another awkward sentence. Maybe:
"...these challenges and dangers are unique depending on both the type of environments being traversed as well as those unique to the specific area."
P9 C1 The Sandbox
"...the Referee advanced timelines..."
"...the Referee advances timelines..."
P13 C2 Rewards
Superscript causes the spacing of lines to be off. 1st level and 4th level.
P19 C1 Time
"...aren't there to simply be a pain the ass,..."
"...aren't there to simply be a pain in the ass,..."
P26 C2 Cosmology and the Gods
"This different sources have different and ..."
"These different sources have different and ..."
Superscript causes the spacing of lines to be off. 15th.
P29 C2 Interaction of Different Cultures
"People fear things different from them, and in worlds..."
"People fear things different from themselves, and in worlds..."
"Merchant and ruling and scholar classes will have..."
"Merchant, ruling and scholar classes will have..."
P31 C1 Breaking the Rules
"...the more potential there is there that players will find..."
"...the more potential there is that players will find..."
P32 C1 Monsters
"...than any of the twenty monsters packing in a forty-room dungeon would be."
"...than any of the twenty monsters packed into a forty room dungeon would be."
C2 Movement
"...and thinking "half/twice/as as fast as a man"
"...and thinking "half as/twice as/as fast as a man"
Perhaps:
"...and thinking "half, twice or as fast as a man"
P34 C1 Humanoids
Superscript causes the spacing of lines to be off. 19th and early 20th.
P36 C2 Magic Items, Point 5: Certain Conditions
Using "certain conditions" to describe "certain conditions" is redundant.
"Perhaps a certain action needs to be taken before the item works (a sacrifice?), certain time periods, etc."
Maybe rewrite the whole sentence.
P41 C2 Replacement Characters
For the three points, the first and third don't have full stops but the second does. Make a decision.
P42 C1 Excellence in Gaming
"...the advice in this book may hinder your ability produce the best game possible."
"...the advice in this book may hinder your ability to produce the best game possible."
Ask Yourself Why
"Strange ideas, perhaps inspired by a movie or odd item in the news, demands to be included in the game."
"Strange ideas, perhaps inspired by a movie or odd item in the news, demand to be included in the game."
..."which helps explain why they can't build anymore."
Either:
..."which helps explain why the people can't build them anymore."
or:
..."which helps explain why they can't build any more."
P44 Compatability Issues
Up until this point you have been talking to the Referee (e.g. You do this...). I think this may be the first time you say "he" when talking about the Referee. ie you change from second to third person. Perhaps it should be:
"All of these games are similar enough to be cross-compatible, but each on has its own quirks and small differences that can trip you up if you are not paying attention."
or:
"All of these games are similar enough to be cross-compatible, but each on has its own quirks and small differences that can trip a Referee up if you are not paying attention."
P48 Fight On! Magazine (I realise you probably got this from the publisher.)
"...that just packs infectious enthusiasm for our form of gaming."
"...that just packs itself with infectious enthusiasm for our form of gaming."
or
"...that is just packed with infectious enthusiasm for our form of gaming."