Traveller has been referred to as hard sf which is interesting for a game with FTL, psionics and reactionless drives. I always thought the reason for that was in the nuances. For example instead of blasters or other rayguns the weapons consist mainly of slugthrowers. Yep, board a ship in Traveller and you're liable to get shotgunned or similarly riddled with bullets till the air pouring from your vacc suit makes you sound like an convulsing bagpipe player. The game's designer defends this concept very eloquently: a bullet is a simple and efficient way to kill a person and likely to be around for a long time.
Energy weapons make two appearances in Classic Traveller, the laser carbine and laser rifle and they are quite impressive and believable. An early laser carbine makes its appearance at TL 8 presumably for sniping or as an amped up targeting system. By TL 9 a culture has developed lasers as their battlefield weapons of choice and developed ablative armor to defend against them. Since laser weapons punch through cloth armor (the defense of choice at TL7-8) a TL 9 soldier tackling a slugthrower wielding warrior in ballistic cloth is at a distinct advantage (laser rifle vs. flak jacket at medium range 3+ to hit, automatic rifle vs. combat environment 8+ to hit.) I like to imagine shiny stormtroopers invading and zapping befuddled ground troops.
But at TL 10 something strange happens. For one thing the flak jackets and cloth armor of earlier tech levels becomes combat environment armor and more effective. More importantly reflec armor appears which works deliriously well against lasers and can be worn with other armors. Laser weapons are replaced by the advanced combat rifle (ACR.) The ACR firing discarding sabot rolls 5+ to hit a flak jacket or 7+ to hit shiny ablative while the stormtrooper's laser rifle must roll a 15+ to hit a trooper in reflec at medium range.
So our invading shiny legions run across a TL 10 culture they might view their slugthrowers with contempt and sneer at their humble bds, till they get holed by the ACR rounds and their laser beams are deflected by the reflec worn under the humble bds.