Here's a jotted-down Soldier class, made for jotting down Soldier characters to battle it out as action figures do.
Obviously, it's just a few steps away from being the standard 5E Fighter...while trying to simplify. In a way.
Saving throws: Strength and [Dexterity or Constitution]
Armor: All armor, shields
Weapons: Simple weapons, handguns, two-handed small arms, heavy weapons, super heavy weapons
Tools: Land vehicles
Skills: Two chosen from Acrobatics, Animal Handling, Athletics, Computers, Demolitions, History, Insight, Intimidation, Perception, and Survival
I'm looking to Dias Ex Machina's Ultramodern5 for guidance here in how to handle the proficiencies of modern warfare. For one thing, I like the way they break down weapon and vehicle categories. Also, while I was initially surprised at "all ground vehicles and aircraft" as tool proficiencies for the Grounder, Ultramodern5's Fighter/Soldier class, I eventually realized that it kind of made sense for G.I. Joe-style characters to be able to handle any sort of vehicle thrown at them. After all, aren't there moments when we just acknowledge, "Oh, yeah, of course Snake Eyes can fly that random plane they found"? Can't think of any specific moments off the top of my head, but...well, at any rate, I actually did eventually figure this should be dropped back to simply "land vehicles." But I digress.
Infantry Training: At 1st level, you treat the effects of exhaustion as one level lower than usual.
Specialty: You have trained for one specific role above others. This may be the use of a certain type of weapon or one of a variety of tasks necessary to the successful functioning of an army. At 2nd level, choose a weapon type (simple, martial, handgun, two-handed small arms, heavy, super heavy) or one combat-related tool and a skill associated with that tool. You gain those proficiencies. If you are already proficient, you gain expertise (add twice your proficiency bonus to rolls).
Second Wind, Action Surge: So, these are basic Fighter features that would seem to easily slot into a warrior type in a miniatures game. They'll almost certainly be on the Soldier ladder, probably with one of them at 3rd level...but I'm not gonna fence myself in just yet. Hopefully I'll make a Level 3+ Soldier before long and have to choose.
More to come soon! (Note to self: Actually write more soon.)