One thing I always like about 15mm is even if you use 24" shoot/6" move it 'looks' right.
Unlike 28mm where it seems like a nerf gun could out-range them. I mean, if a 28mm/1" mini is ~2m then guns if to scale would have a hard cap at 24"x2 = ~50m extreme range!
However I'm about to commit the same sin I decry. You see my tankmunda tank-centric warbands of ~6 tanks need a compressed scale to fit.
I say 24" is ~1000m or the 'normal' range most armour/gun values are measured at. Upper range depends on the gun - higher velocity bigger guns like 88mm PaK would shoot to 48" (2km) where most normal 75s would cap at 36" (1.5km). This allows bigger guns to reliably out-range and out-shoot on our 4x4 or 4x6 table and 'fits' with conventional wargame ranges.
However, I am using small squads of infantry. They are used to seize objectives and loot aka "scrap" - a catch all for valuable resources in the post-apocolptic landscapes of the 1930s-40s, where overuse of gas in WW1 has created a hellscape of mutants and zombies.
The aim is a mix of Frostgrave/relic hunting and Dropfleet Commander using vehicles to ferry troops.
Now if 12" is 500m that makes normal small arms ranges quite short! Even for 15mm...
Support weapons like sniper rifles or LMGs might go 18"....
I kinda handwave the short ranges in tanks as vision in WW2 era tanks was very restricted. And given most tanks can comfortably shoot across most of the table anyway (albeit at a penalty if over 24") shooting tends to pivot more on crew skill (pass crew test to acquire targets or get extra actions to aim carefully).
But 15mm rifles shooting 12" irks me as much as 28mm rifles shooting 24".
Also there's infantry spotting range to consider - stationary infantry in cover may not even be visible at 500m especially if I use some sort of "gone to ground"/hide mechanic where you forgo shooting to regroup/stay safe.
So normal rifle guys exchange fire at 12" (500m) but are safe beyond it. If someone hides/goes to ground they might only be able to engaged at 6" (250m) or less! Given the game is designed around tanks, it's probably OK. Infantry are mostly to hold objectives and retrieve warpstone/relics/scrap so they probably should be hard to spot and wrinkle out of ruins and heavy cover.
OK some quick rules.
Troops are in fire teams of 4-5; or less for a weapons/sniper team.
Say 3+ or 4+ to hit (-1 cover, -1 if suppressed) with troop training making a "save" of say 3+ (veteran) 4+ (regular) or 5+ (green). Maybe save modifiers of +1 if in cover, +1 if heavy armour. Normal rifles shoot 12" x1, SMGs 6"x2, and LMGs 18"x3-4. So far, so very Bolt Action/Flames of War/40K.
Troops can either move or shoot in any phase of the tank turn. Movement is 4" (or 3" if armoured).
If troops take any hits (even if saved) they are suppressed, and must make a crew check (3+.4+ or 5+) in order to move or shoot: or else they skip their turn to recover/remove the suppression (hiding and recovering). One suppression token per source of hits (Bolt Action?) = you only get one suppression max for each unit per phase attacking regardless of hits.
If troops take any casualties once have taken 50% or more; pass a crew check or remove unit. Likewise if suppression tokens exceed current troops in unit.
Some sort of 'hide'/'recover' order where perhaps you can re-roll any saves to block hits but can still accrue suppression normally? Maybe to 'recover' roll a crew check for each suppression token and remove one each success. That way better troops survive and function under pressure better and recover faster.
Ok pretty generic but I literally recalled invented them as I typed. Creativity is overrated - the aim here is to be easy to explain, and 'slot-in' to existing rules. In addition, I can be pretty confident it will work out the box with perhaps a +1/-1 modifier here or there to tune the lethality.
These 15mm are painted too dark. They need to go 'one shade brighter' but I haven't got to that yet as I got bored with their teensy details and I have school planning to do. Still count as tableworthy, but I'll probably circle back to them when I'm in the mood. Still have 30 or so insurgents/Chechyans/Soviet militia to go....
Hmm while12" gun range irks me, it may be OK themastically. In the post-apocalyptic 1930s-40s world, troops are transported by tank or halftrack to their destination, which is invariably scavenging in city ruins, so there is a much higher proportion of armour, as well as gasmasks/NBC-esque gear and automatic CQB weapons. Think the mech suits from Fallout or Soviet engineers in breastplates with SMGs. I'm largely using GZG sci fi infantry in the role.