Introduction

This mod aims to do two things. First, to add a variety of visually distinct and interesting spidertrons into the game, with their own characteristics and gameplay considerations. Second, to make accessible to you the generator template that was used to make these spiders in the first place.

Spiders

There are currently a few different kinds of spiders the mod adds:

• Basic spiders
  Accessible relatively early, unlocked by the Basic Spidertron Tech and subsequent tier unlocks. They do not provide much utility other than being cute and providing some means of transporting the player in style.

• Utility spiders
  Larger, slower, 10-legged beasts with no weapons but large inventories and equipment grids. These will help the player construct the base if you give them access to resources and construction bots.

• Combat spiders
  Faster, menacing, and loaded with progressively more rocket launchers, up to the vanilla 4. They don't have a lot of inventory space and have smaller equipment grids, but these will make quick work of the biters pestering you.

• Prime spiders
  Ever wanted a spider with a prime number of legs? Wonder no more, with this Prime research you will unlock spiders with 2, 3, 5, and 7 legs! Each have their own quirks and showcase the abilities of the spidertron generator.

• Eldritch spiders
  The Abominatron stretches the boundary of what is considered a practical means of locomotion.

The Spidertron Generator

The mod uses its own code to generate spidertron prototypes based off a standardized template structure. Technologies and recipes are largely added by the mod itself.
To start tweaking your own spiders, you must find the spidertrons/spidertron_variants.lua file in the mod directory. In there, copy one of the already-present templates (they start with "name" and end with the "resistances table"), and tweak the values to your heart's content!
Most of the values are self-explanatory, but I encourage you to experiment and see what happens.
Here is a list of the parameters:

name: the internal name of the prototype, must be unique to other spiders
order: orders the spider in the GUI, doesn't appear to do much though in my experience
scale: the overal scale of the spider, including the body
height_offset: a linear offset placing the torso higher (positive values) or lower (negative values).
leg_scale: scales the legs without the body, thickness, length, and how far the legs are from the body on the ground
leg_thickness: a multiplier on the leg thickness, 2 is twice as chonky, 0.5 is twice as lanky
knee_height_offset: linear offset placing the knees of the legs higher (positive values) or lower (negative values)
knee_distance_from_torso: the factor determining the ratio of the segment from the torso to the knee and the knee to the ground for the legs
speed: the speed with which the legs move from point A to point B, does not influence speed of the spider directly, only indirectly
step_size: the base distance each leg moves from point A to point B
movement_based_position_selection: the distance the legs move in the direction you are trying to go, for best effects must be larger than step_size
leg_count: the number of legs of the spider, if you alter this, you must edit several other tables as well
leg_ground_position_scaling: a multiplier on how far from the body the legs are on the ground
tarantula_factor: a value used by the table after, used to scale individual legs further or closer to the body
is_tarantula_leg: a table of numbers representing how much the tarantula_factor must be applied to each leg - must therefore have an entry for each leg! 0 means no change, positive values make the leg move further from the body, negative values make them move closer. You can make asymmetric spiders with this, if you wish
mount_angles: a table containing the angles where the legs must attach to the body, in degrees. 0 is right, 90 is down, 180 is left, 270 is up.
ground_angles: similar to mount_angles, but determines the base position on the ground instead. usually will be the same as mount_angles for best effects, but if you want completely misformed and mismatched legs, you can!
walking_gait: a table containing the walking_group number for each leg. legs in the same walking group move together. respects the same order as the angle tables, so you can visualize which legs you're assigning to which group.
leg_sprite_rotations: a table containing the leg sprite factorio assigns for each leg. must be a number from 1 to 8 for each leg. Not a great impact, just make sure there is an entry for each leg.
body_shadow_offsets: this mod uses custom body assets from the Tarantulator mod (https://mods.factorio.com/mod/tarantulator), which means that the shadow is not automatically shifted to the correct position. use these values to tweak the body shadow to align nicely with the leg shadows
equipment_grid_width/height: the width/height of the equipment grid the spider should have
max_health: self-explanatory
inventory_size: self-explanatory
guns: self-explanatory
automatic_weapon_cycling: whether the spider should automatically cycle through weapons, if they have any
role: ID that determines in which technology branch the spider will be placed in. currently accepts "basic", "utility", "combat", "prime", and "eldritch". used to generate recipes and technologies dynamically
tier: the general tier of the spider, used to determine science cost and recipe ingredients. currently accepts 1 to 7
resistances: self-explanatory

Compatibility

The mod is written to be maximally compatible with any mod. (inb4 a billion bug reports). The vanilla spidertron tech is removed, unless you have the Space Spidertron mod installed, in which case it only removes the recipe.

When playing with Krastorio 2, Space Exploration, and/or some of Brevven's resource mods, the ingredients for the spidertron parts will be automatically adjusted, along with moving the tech prerequisites to adjust for the new recipe.
In fact, the technology and recipe assignment code is written in a way that the spidertron technologies will always be dynamically assigned prerequisites depending on the necessary resources to craft them. Therefore, add as many mods as you like. If you find something strange, I'd love to hear it, and to fix it!

Conclusion

This mod is currently in active development and there are still things I wish to parametrize into the template, but I felt like getting it out there would be good. Please provide feedback in the discussion tab, and suggestions or feature-requests are welcome also. If you add your own spider templates, make sure to save them somewhere before you update this mod!

Many thanks to the Start With Spidertron mod (https://mods.factorio.com/mod/ProtoSpidertron) for the inspiration and which had some code I used as a base, and to the Tarantulator mod (https://mods.factorio.com/mod/tarantulator) for the visual assets and inspiration to develop the tarantula factor code!
Thank you for your attention, and I hope you have a lot of fun playing with the new spiders, and generating your own!