Okay, I'm playing in Ultra-Violence as Dimitri Paramo this time (the slow-but-tough player character, that's why it kinda looks like if he was walking). You can see that weapons work a bit different for him. The Assault Rifle fires faster, but inaccurate, so does the Shotgun, and the Chaingun fires much slower, but launches 2 bullets per shot. Also the Missile Launcher throws heat-seeking missiles at opponents. In case you cannot tell, the orange-tinted screen means that the Disruptor Shield is in effect (you can toggle shields on and off at your will, as long as you have enough charge). You can notice that while it is active, the blue bar on the Status Bar goes down slowly (this is the charge meter). Also, brown Demon Troops don't harm me with their distance attack, however black ones can still cause damage. Shields can be recharged by picking up energy cells. These give you Cell ammo AND Shield Charge.
About armors, we know that there are not armor bonuses here. So, they work much like in Quake 2, where picking up a lower-level armor than your current one is used to repair it. This means that if you have a Guard armor (yellow, 100 points) which is a bit damaged, and you pick up a Duty armor (green, 50 points), the Guard armor's points will be restored a bit rather than being replaced entirely by the lower level one.
Speaking of the level, you will notice that I already have the Red and Yellow keycards and the Colonel's Hand (made a quick cheat for the sake of this demonstration). The yellow card is necessary for reaching this level, and the other two are needed for accessing each one of the two guard posts. Even if you have all card keys, you need the Colonel's Hand to be able to flip
the switches inside the guard posts, so you have the "clearance" needed to operate the final Monorail Car. In short, you need all non-secret keys to finish this level.
The message you see at the start ("Monorail to Mines' power restored.
") is the one you get if you passed through the Power Plant and restored power to all the base before reaching the Lab. If you didn't, the final Monorail Car will not activate and will tell you to go back and get the Power Plant running.
At one point, you see I exit the level and go to Supply Depot 1. This is where you need to go if you want to get the Blue key card. Even if you exit the map, you see that the time for the map "freezes", so it waits for you to come back to continue (in case you wish to beat the par time. Of course, beating par times grants you a special score bonus).
And finally, I didn't spoil any secrets, however, I will tell you something: the door that needs a "demonic DNA sample" needs a secret, special key hidden in this level.