The TC itself is an auto-extract pack, for DOS or Windows. With Windows, you can use a very good launcher which gives you access to a lot of options, like a training camp (but unfortunately, the didactic dimension of the latter is a bit botched). In the DOS version, the launcher is a bit more sober and allows you to do the same things.
The game begins with a race against time : you are in the cockpit of your ship, which has been badely damaged by the arachnides. You have 5 minutes to make your way toward the hold of the ship, where you can find an escape pod. Meanwhile, a rather annoying alarm jingles all the way ;-)
Once you have been ejected from your burning ship, you must (to sum up) find the other starship troopers, then kick some arachnides' asses and eventually kill their "queen". To do this, you must go through 3 episodes, which is sometimes utterly impossible. Each episode contains a few missions, and generally, after a mission, you go to a troopers' base in order to pick some guns and medkits.

However, the monsters are disappointing, because of the lack of diversity : the main monster is a 6 feet tall arachnide, as clever as an oyster, and put everywhere in the game. But there are some variants : some arachnides spit acid, a few others only use their claws... You'll see some flying arachnides too (which are quite annoying), and of course, a few bosses... Have you ever seen a 150 feet long spider ? :) By the way, the creators of the TC sometimes wanted to privilege a fast game : in some places, the arachnides will been spawned indefinitely (well, until the game crashes), forcing you to rush toward an upper place so as to hide.
The weapons are rather well designed (except one or two of them) and their strength is just powerful enough to eliminate the spiders (which are more and more numerous and dangerous as you go through the levels). But there's an exception to this linear increase of the weapons power : instead of the RPG, an atomic nucleus launcher (given too early in the game) destroys everything within a radius of 100 feets. In my opinion, this item should have been given as a special weapon against the last boss.

Concerning the design, I hope you like the outside areas and the dark and mazy caves : it's 80% of the game ! Sometimes, it's very easy to lost one's way in the underground areas, which are very dark (even with the max gamma correction). It's a pity, because it is really annoying and kills the fun.
Most sounds are new. Of course, it includes the indispensable radio conversations with Tachcomm, the growls of the wandering monsters and the explosions. As for the graphics, there are minor changes, as the rock wallpaper from the original Duke has been set almost everywhere ! Well, there are still new stuff inside the buildings, like the transparent doors, the seats, the computers and so on... These new items are good stuff, and in contrast to the exterior "default" design.
Something is very annoying : the BUGS !! For example, with the 0 weapon (freezer), you shoot in a high cadence some energy balls which split up at impact. If you have launched an atomic explosion just before using this weapon, the combination of the atomic fire and the hail of energy balls will crash the game in 5 secondes (because of the amount of sprites) ! Well, everyone won't necessary encounter this bug, but there are some bugs in the levels themselves (for example, a sloped roof which kills the player when he passes underneath) ! Even if Duke3D contains some bugs too, the one of this TC are much more numerous, and spoil a bit the game.

GRAPHICS : 6/10
It's often the same things on the outside, but broadly speaking, it's good stuff.
ATMOSPHERE : 9/10
Very thrilling, the player is sometimes near the heart attack when the arachnides suddenly scream !