In gaming, at least, I've seen "microtactical" used a long time ago for any game that focused on individual figures (and this paralleled but was separate from RPGs).
Yeah, it's been used that way.
Actual maneuver doctrines currently set the fire team as the fundamental tactical maneuver unit, be it 3 or 4 man, in the US. Prior versions used fireteams ranging from 3 to 5 man. Last I checked, USMC was 3 man, and US Army 4 man; USN and USAF infantry and infantry equivalent forces usually match USMC and USArmy, respectively.
Up through WW II, the Navy maintained infantry training as a standard part of the BM, GM, and MA rates, and the deck department seamen non-rates (SR, SA, SN). Signalmen often also got infantry training. See the LPM from those areas. There are still provisions in the LPM for naval infantry, but I don't know if they're trained outside the crews of the littoral combat ships.
Interesting, thanks. By that definition, it still wouldn't apply in my "20 people in the face of the enemy" scenario.
It would if there is a fortification or cover source, or some other resource linked to the position, such as a boat to board, that is the reason you are moving to it.
Also note: Fortification, in a modern infantry sense, includes everthing from a foxhole to a bunker, and lots between. The Russians and Ukrainians are using trenches currently, for example.
Cover is a tactical positional goal, not a strategic one.
For example, a move from open field into a stand of shrubbery or a garden wall, provided it isn't changing the targets available, a positional tactical movement. Its movement to take advantage of specific locations resources, whether in a tactical or strategic consideration.
As is movement to get off the command detonated minefield. Positional vs engagement movement are a different axis from tactical/strategic. Much tactical movement is for positional benefit. Much also is for access to targets. The move is not positional if it's about changing the available targets for your fire.