Full Metal Bones is the demon that lives in my head and tells me to make a mecha game complex beyond reason. It started out as a simple idea for the "New Beginnings" game jam on the previous version of Paper Cult -- a ttrpg forum. The initial premise was just "hey I should make a mecha game" because I love mecha so much.

Unfortunately, a lot of the initial design work was lost when the first version of PaperCult shut down (not that I had written much). By the time I got around to revisiting the idea, I had different design goals in mind. Currently, a lot of the basics are in flux: changing as I get new ideas for them. I've written a handful of posts about Full Metal Bones but even now I'm tempted to hack them into something new based on a cool initiative system I heard about.

Between the two games I'm working on, Full Metal Bones has had far less dedicated focus and effort into making it coherent. I work on FMB whenever the inspiration strikes me, and it will probably stay that way until I publish a working version of The Serket Hack.

Pilot giant fighting robots powered by reactors that burn SIN and lose your body to the machine. Kill fascists and capitalists. Engage in incredibly dense combat mechanics based on high-speed mecha battles.

The central design of the game is based around creating combat mechanics that could only be for a mecha fight. Thruster speeds, target locks, and armor density are the important attributes. FMB also has a focus on providing a large amount of options for machine customization: I want enough substance for a healthy buildcrafting / minmaxing playerbase.

There's a lot of flavors of mecha, but Full Metal Bones is influenced by two in particular:

• Armored Core
• Mobile Suit Gundam

Armored Core is what I want the speed and customization to feel like. Gundam is an influence because I want to emphasize the difference between mass production units and "special" machines.

My initial plan was to have mechs divided into two categories: mass-production units and custom-built rigs. Each would have a different dice resolution system with unique ways of probability manipulation centered around fuel expenditure. The amount of SIN rods activated increases combat effectiveness but they need to be rationed throughout a mission.

Currently the two types of mechs use similar mechanics but have different reactors which provide unique energy economies. Mass production units generate energy per turn and use that energy for maneuvers and weapons. Custom rigs generate heat based on the amount of active SIN rods and that heat needs to be kept under a certain level by using it for maneuvers and weapons. Essentially this means that custom rigs have to "ante" for battle and wager how much they think they'll spend, but otherwise have an easier time getting the fuel they need than mass-production units, who are more "slow and steady".

As of 05/11/2025, I have yet to make a post about the new initiative system I've been thinking about adding. The basic premise is that each part of the machine has its own initiative, and all combat participants take turns simultaneously. For example, a machine pistol might have d4 initiative, capable of activating in rapid succession, while an autocannon might have d12 initiative, making it three times slower than the machine pistol. Thruster parts have "static" initiative that govern how frequently the mech can change directions.

Conceptually this is both crunchy in terms of builds and requires high processing power on behalf of the players. It almost definitely would work better running in a VTT. I'm still interested in putting together a playtest for it because I think it would be fun.