Mech Homebrew

by Nab

Search GM Binder Visit User Profile

Built to Smash

Table of Contents

Table of Contents

Part 1

Mech Creations

Mech Creation

Mechs are large mechanical constructs of a wide array of profiles and powered by a variety of mundane and magical sources. Though mechs may be utilized in an array of duties, they are often fielded in battle with different designs for specific combat roles.

Power Source

Mechs are classified by their power sources. By this measure, five types of mechs exist: steam-powered, man-powered, clockwork, animated, and undead.

Steam-Powered Mechs

Steam-powered mechs are the most prevalent. The first mechs to be built were steam-powered, and most new mechs continue to use steam as their power source. Dwarves and humans are the predominant users of steam-powered mechs. These mechs are durable and rugged, but labor-intensive and vulnerable to mechanical mishap.

Man-Powered Mechs

Man-powered mechs are primitive constructs that mimic the mech’s physical shape and abilities using a more antique engine — human labor. The typical man-powered mech requires dozens or hundreds of slaves toiling ceaselessly to keep it running. Orcs are the only race to use man-powered mechs extensively. These mechs are slow, cumbersome, and vulnerable to slave revolts.

Clockwork Mechs

Clockwork mechs are in many respects similar to steam- or man-powered mechs, but their precision craftsmanship and extraordinary construction set them apart.

Clockwork mechs are powered by springs, pendulums, and other such mechanisms.


What makes them special is the exactitude of their design. A clockwork mech is periodically “wound” like a clock. For several days thereafter, all the power it needs comes from the unwinding of its mechanisms. Every single component of the mech is connected in an elegant, complex symphony of brass and steel. The winding process requires extreme force — generally, it entails turning a massive spring running the height of the mech — and the clockwork mech incorporates steam or manpower once every few days to wind itself. Outside of this “refueling process,” however, it runs on its own power. Clockwork mechs are extremely powerful and extremely rare, having been seen only in the hands of master gearwrights.

Undead Mechs

Undead mechs are a rarity. Known only through anecdotal evidence, these massive mechs are rumored to be the reanimated, reconstructed remnants of massive skeletons.

Part 1 | Mech Creation
Mech Traits By Power Source
Type HD Str Dex Ref Fort Speed CN MNVR
Steam High High Low Low High Average Average Average
Man Average Low Low Low Average Low High Low
Clock High High High High Low High Low High
Animated Low Low High High Average High Low High
Undead Low Average Average Average High Low Very Low Low

Profile

A mech’s stats are defined in the traditional monster format. They have hit dice, attacks, damage, and ability scores, just like any construct. A few new terms apply to mechs, however, and a few old terms are defined differently, as follows.

Hit Dice

All mechs use d10 for hit dice, and they always receive 5.5 hit points per hit die.

Speed

Mech speed is listed in tactical terms, as with normal monsters. Large mechs can move great distances quickly due to their massive strides, but in general, mechs are not capable of high-speed movement.

Speed Conversion Tables
Tactical Speed Overland Speed
30 ft 3 mph
40 ft 5 mph
50 ft 6 mph
60 ft 7 mph
70 ft 8 mph
80 ft 9 mph
100 ft 11 mph
120 ft 14 mph
140 ft 16 mph
160 ft 18 mph
180 ft 20 mph
200 ft 23 mph
220 ft 25 mph

Armor Class

Armor Class isn’t relevant in most mech combat. Each mech has an armor class, but due to their size, they are often painfully easy to hit. More important is the mech’s hardness, which is a function of its size and material type.

Hardness (Ha)

A mech built of iron is more durable than a mech built of stone. This is reflected in the mech’s hardness score. Similarly, a Colossal size mech has a denser superstructure than a Large mech. It also has more open space, meaning a successful penetration is less likely to hit something important. All of this is reflected in the mech’s hardness rating. Whenever a mech takes damage from any source, the damage is reduced by an amount equivalent to its hardness score.

Critical Thresholds

A heavily damaged mech may suffer system failures long before it is completely destroyed. Mechs have what are known as critical thresholds. These are divisions of their hit points. At each new threshold, the mech is more likely to suffer critical hits. Critical hits cause not only additional damage, but also specific system failures (such as a loss of power to the right arm, or clogged gun ports). Each mech has four thresholds: green, yellow, orange, and red.

Part 1 | Mech Creation

A mech’s entry will include break points, as a percentage of total hit points, for these critical thresholds. For example, “Green, Yellow 50%, Orange 25%, Red 10%” means a mech crosses the threshold to yellow when reduced to 50% of its starting hit points, orange at 25% of its total, and red at 10% of its total. Extra damage caused by a critical ignores the mech’s hardness since it takes place inside the mech’s shell.

Attacks

A mech’s attacks depend on its crew. Even though a mech may have many attacks listed, it needs the relevant crew members to be alive and functioning in order to make those attacks.

Space/Reach

The height of a mech is determined by its size, as indicated in Table 2-2. The height may vary by up to 10% of the indicated measurement with no change in statistics. The face of a mech is generally equal to 1/2 its height, rounded down. The reach is 1/2 the mech’s height. Again, the exact dimensions may vary based on the mech.

Saves

Mechs have Fort and Reflex saves. A mech’s Fort save applies to effects that call for Strength saves. A mech’s Reflex save applies to effects that call for Dexterity saves. A mech’s Reflex save (which is almost always negative) is not inclusive of Dexterity modifiers.

Ability Scores

Mechs have Strength and Dexterity scores. Both are contingent on the mech’s size and power source. Some mechs may be clumsy but powerful, while others are agile but weak. As their “vitality” comes from their pilots, mechs do have a Constitution score. Mechs also do not have Intelligence, Charisma, or Wisdom scores. The mechs

Part 1 | Mech Creation

themselves are never subject to effects or checks concerning these stats; such effects or checks instead affect their pilots and crews.

Payload Units (PU)

This new term describes how many people and weapons a mech can support in addition to its basic superstructure, armor, and engines. One Medium creature or weapon takes up one payload unit, a Large creature or weapon takes up two payload units, a Huge creature or weapon takes up four payload units, and the progression doubles at each increment thereafter.


Living space (for city-mechs) requires additional payload units. The absolute minimum is living space equal to the creature’s PU (e.g., a Medium creature would require 1 PU for workspace and 1 PU for living space). This is slavelike housing — just enough room to lie down beside a workstation. Normal mech living conditions require double the creature’s PU (e.g., a Medium creature requires 1 PU for workspace and 2 PU for living space). This is still quite cramped but at least includes enough room for a bed and a few possessions. Aristocrats, mech jockeys, senior engineers, and high-ranking military officers generally have 3 or more PU for living space.


Payload requirements for common spaces (kitchens, marketplaces, mess halls, recreational areas, etc.), are assumed to be included in the normal living space as an averaged figure. This is an abstraction, but it makes the mech-design process simple and fast.


Payload requirements for weapons generally include space for ammunition and reloading, unless noted otherwise. The mech itself occupies a space equal to twice its payload units. For example, a Huge

mech stored onboard a city-mech would occupy 8 PU. Payload units can also be used for transporting raw materials. In general, 1 PU is sufficient to carry a volume measuring roughly 6x6x6 feet (216 cubic feet), or weight of 1,000 pounds.

Crew Needs (CN)

Different kinds of mechs require different kinds of crews. Man-powered mechs are extremely labor-intensive since the entire mech runs by manpower. Steam-powered mechs also need a lot of hands-on board to keep the fires stoked and maintain machinery. Animated mechs require substantially less crew (mostly just gunners and tactical staff), while an undead mech requires only a single necromancer to control it. A mech’s profile will indicate its crew requirements.

Firing Ports (Fp)

In a small mech, all the passengers are near the edges and can fire ranged weapons through firing ports. The larger a mech becomes, the lower the proportion of its passengers that is near the edge and has access to firing ports. The firing ports entry is determined by a mech’s size. It indicates what percentage of the mech’s total payload units are next to firing ports. Remember to add vertical height into the range determinations for shots fired from high up on large mechs.

Power Source

As described above. A mech’s entry includes a definition of the power source that runs it.

Cool Title

Write Something Cool Here

Part 1 | Mech Creation

Size

A mech is constructed by determining its size and type, customizing various components, and adding weapons. Construction will be described in more detail later, along with information on pricing. For now, let’s look at the various components of a mech’s profile. The first consideration in a mech’s profile is its size. This determines the range of its payload and height. The type when combined with the size then determines the range for the rest of the attributes. A mech can exceed its normal size/type range, but this raises the cost. The “size modifier” applies to the mech’s AC and melee attack bonuses. Each individual mech type has its own profile based on its size, as follows. These profiles include critical hit tables for each mech type. These critical hit tables will be explained in more detail later

Typical Mech Traits By Size
Size Payload Units Height Size Modifier Hardness Firing Ports Unarmed Dmg
Steam High High Low Low High Average
Man Average Low Low Low Average Low
Clock High High High High Low High
Animated Low Low High High Average High
Undead Low Average Average Average High Low
Steam High High Low Low High Average
Man Average Low Low Low Average Low
Clock High High High High Low High
Animated Low Low High High Average High
Undead Low Average Average Average High Low
Steam High High Low Low High Average
Man Average Low Low Low Average Low
Clock High High High High Low High
Animated Low Low High High Average High
Undead Low Average Average Average High Low
 

This document was lovingly created using GM Binder.


If you would like to support the GM Binder developers, consider joining our Patreon community.