Basic:
Grunt. these are the standard, basic, expendable infantry. The Empire throws these clones at the enemy in vast numbers, spending them as if they were grown in vats. And not hte good vats, either.
infantry:
Soldier. a slightly better version of the Grunt. More professional, better trained. A slightly improved to-hit chance, able ot pick targets. better armor and more precise weapon
Heavy Grunt. Like the soldier, except more brute force, whereas the soldier is more professional. These hit hard in melee and soak up damage. can carry an additional weapon of player choice
Grenadier. A Grunt with a good throwing arm and enough sense not to pull the pin to pick wax out of his ear. usually.
assault gunner. a soldier that carries a full auto, high energy weapon. good for suppressing fire, chewing through defensive structures, and cutting down trees. Not the most accurate of shots, so try to stay behind these guys.
Shooter. Where the assault gunner shoots lots of bullets toward an area, the shooter is more of a sniper type, taking long shots with careful aim.
point manbonuses to perception and reaction, takes the front in travel and scouting
(esentiially, the soldier is the middlle of this class system, and each of the others improves one type of action at the expense of others: heavy grunt is melee and strength, assault is lots of innaccurate shots, shooter is pre -sniper, grenadier is explosives. Point man is a sort of scout, and pre stealth)
specialists:
demoman. carries the big booms. Blows shit up. usually needs some body guards, due ot being priority targets.
support:
medic. experts in clone organs, limbs, and combat surgery. these guys will stitch you back together on the fly, on the run, or in the hole. Try not to look too closely at the gift organs. These guys are not scrupulous about whee they harvest from.
Chaplain. Space Jesus loves you. These guys, on the other hand, are a few proverbs short of a parable, a few psalms short of a prayer book, a few chapters short of a Testament. But what they lack in sense, or sanity, they make up for in Faith. And badassery (see the prestige class, kung fu zealot)
tunnel rat. get in the hole, root out the hole dwellers. try not to die. but if you do, at least you are already underground. Saves on burials.
communications. Like to talk? Completely useless with a weapon? Able to spell your own designation on the first try, almost every time? Coordinate your fellows, and keep in touch with your commanders. use a radio,headset, telegraph, optic network or subspace relay to give the Empire the strategic advantage of coordination.
not yet implemented: sniper, pilot, heavy weapons, artillary, tank guys, mech commanders, robotech ...
I had Chaplain and Kung Fu Zealot misnamed - they weerewhat I meant by priest and kung fu priest.