Judging from the movies, Imperial Stormtroopers are lousy shots and poorly trained in combat in enclosed areas (towns, ships, etc.) They have very little training in practical infantry tactics. Then again, the same can be said for the Redshirts among original Star Trek crews.
For a realistic sci-fi game, units of regular and elite troops would have to be formidable thanks to equipment, training and support. These troops would have protective gear, reliable weaponry and appreciable combat skills. It is useful that these would include:
Use of cover and concealment
Marksmanship
Use of extra weapons such as hand grenades.
Close combat skills, both unarmed and using hand-held weapons
Practical fire team and squad tactics.
Use of various infantry weapons: pistols, heavy rifles, small rocket launchers, etc.
Scouting and Patrolling
The ability to assess and respond to enemy action
The ability to coordinate one’s actions with other team / squad members
The ability to communicate with other members of one’s army
These are basic skills, the equivalent of which are taught in modern basic training. Advanced versions of these skills are common among regular combat troops.
Among advanced skills are fighting techniques adapted to various types of terrain. These may include jungle, grassland, tundra, sand and stone deserts, forests, and swamps. Sci-fi scenarios would also include combat in low atmosphere and low gravity environments. Combat in aquatic and subterranean environments may require specially-trained troops.
Unless they had good training and discipline, a platoon of Rebels would be at a disadvantage against a squad of Stormtroopers with realistic fighting skills.
Remember also the ability of Imperial troops to call in support and reinforcements from larger units.
In an OMOG game, imagine a Stormtrooper unit of nine to twelve men. It will have a commander, assistant commander, regular weapon teams (equivalent to rifle teams) and a heavy weapons team (equal to auto rifle or LMG team). There may likely be some sort of rocket-propelled or simple grenade launcher. Imagine that at first contact, the squad has alerted the next level of command. This means that in a number of turns - maybe ten or twelve - more troops and weapons may intervene. The Rebel unit has to accomplish its mission before Imperial support arrives.
Stormtroopers, may also be standard enemy infantry / marines, Peacekeepers, Scarans, etc. Rebels may also be mercenaries, etc.
Rebel and irregular forces usually have inferior arms, mixes and incompatible weapons, and limited supplies of ammo and support. Imperial and other government forces are part of their government supply chain and have abundant ammo and other resources. This includes the ability to operate in different environs, etc.
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The problem with Sci-Fi writers is that they have no experience with military matters, especially in these days. When designing a government army, they should look at current counterparts. I would suggest downloading one of the soldiers’ basic skills manuals from the past 40 years. Also, a manual on the infantry squad and platoon. and one on scouting and patrolling. Various such manuals from World War II to the present can be found online. If a writer wants to write about armored vehicles or artillery, he ought to acquire basic information on the operation of modern tanks, personnel carriers and artillery units.
It stands to reason that futuristic infantry, armor and artillery will evolve from the lines established for its current counterparts.
There are ways that armies have fought through the ages. Modern armies have evolved to current modes of warfare. What may the future bring? What may be available in a futuristic, distant part of the galaxy that evolved differently from Earth?
Another monkey wrench in the works: how would different cultures affect the way soldiers fight? In World War II, Japanese culture supported suicide attacks. On the other hand, the Israeli army does everything it can to protect the lives of its soldiers because of its far more limited manpower.
This much I can assure you as a veteran: the regular army forces of a government will reflect its leadership in terms of training, equipment, leadership and support. Armies of stable governments tend to be well-trained, well-led and well-supported. They can fight well. A ragtag bunch of rebels would have a hard time confronting such a force. Rebels may pull off a small raid or ambush infrequently, but they would find themselves outmatched by a well-trained and well-led government unit.
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Star Wars, Star Trek and other militaries are made to look good on screen. Their primary purpose is to entertain within the parameters of their respective franchises. We cannot easily equate the weapons carried by sci-fi characters with their Earthly inspirations. The standards are not so much how an effective weapon might appear, but how cool a weapon looks.
