General:
You entered the base of the extincted people!
The base instructions for the first room:
Aim with the transducers (window things) towards the conductors (orbs) to build an event chain.
Each time a Skaarj Projectile hits an orb, the corrensponding transducer will fire and something else will happen in addition.
To get some Skaarj Projectiles ring the bell (shoot at it) for help.
The stair coming out of the floor when the fifth conductor is powered is not only a stair to go up to the platform,
but it is more a lift to go down to the underworld.
Kill the Queens one by one to get the platform down and get more ammo.
Don't use up the Shield Belts all at once.
When you play via internet you may have troubles entering the paternoster:
because of your ping you enter too late and thus fall between wall and cabin into the slime.
A ping of e.g. 330 means your walk command is received by the server about 1/3 second later.
So you have to enter the cabin 0.33 seconds before you see it is best.
The turning walls maze near the end consists of three carousels which are exactly same.
The third one has two levers in the hidden hallways opening the bars of the corridors each.
In multi player the most easy thing is when one player pushes the buttons
and the other one turns with the carousel and pushes the levers.
In single player you may turn the third carousel until you can push the lever to the right of you.
Then push the right button once again and turn back the way you came to the other side of the third carousel.
Now the bars are opened and the second lever is reachable which opens the bars blocking the ending corridor.
Tips:
To aim the transducers: It follows your yaw and your pitch (up to certain limits).
Watch your eye height and the height and angle of the two spires.
Consider that two projectiles will be fired in parallel lines.
Often one misses the aimed orb left of it and the other one right of it.
The second transducer may be targetted to the fifth conductor directly (then you don't get the stinger).
Don't turn the transducers towards yourself. You will be crushed.
Move smoothly and turn softly (use your walk and / or duck key).
Don't encroach the stairs.
Don't touch the walls of the turning carousels!
The pool between the second and the third carousel is a healing pool. You can't even drown in there. Relax!
Secrets:
Did you find the ASMD and the Razor Jack near the first room?
There are hidden goodies in one of the carousels (multiplayer-reachable only).
Read the translator message!
To get back without help push the button and enter the carousel before it starts turning.
But watch out: It turns two steps at once.
... and some more ...
