My first impression is that I love the chopped together monster mech on the cover page. I just wish you had used a lion's side profile while roaring to really sell the lazer/whatever it is breath weapon attack. 

The character creation rules feel really special. Building out your monster mech piece by piece and then assigning attribute points based on the pieces you picked is a great way to let players fully control what their mech is while also ensuring it fits nicely into the mechanical game system. One major concern I have is the amount of time it takes to build a character. Maybe to streamline this process, you could have some monster part tables to select from and/or some prebuilt monsters. 

I do wonder if the way you use the monster scores/mech scores does potentially encourage some level of min-maxing. For example, to me it seems like it would be optimal to make a monster out of either 5 parts monster or 5 parts mech, then flavor all of your narratives toward the side you're strongest at. I think maybe you should consider that the minimum mech/monster score is 2 to avoid the extremes.

I really like that you give the players options to build their own systems to attach to each body part, but again, I worry about how long it takes during combat. I think trying to have some prebuilt options to pick from for each body part would streamline the experience. 

I do agree with some of the other comments that the existing doc mostly focuses on how to build your monster mechs with less detail on how to use them. I would definitely like to see a version of this with the rules fleshed out in more detail. I think the damage/injury system could be clarified, as well as adding ways to spend dice. 

Great submission!

Feels like some nice and detailed self-balancing rules to construct a mech. I think working out my monster mech conceptually and mechanically would be the fun part (and is where the focus is).

I could see this working almost as a drop-in in another game? Like otherwise normal sized characters suddenly got involved in a mixed up mech/kaiju situation, this would add some nice structure to that.