Shoot the... whatevers on top of the columns, then jump on the middle bar. Shoot the pretty face over the door, and ride the middle bar up. Take secret #2 and the cell boxes, then jump down and dive under the middle bar - this is the real secret area.

If something fouls up, just shoot the face again. The switch works as many times as you like.

Well, now you _are_ up here... Jump to the ledge opposite the... whatevers, and edge to this bit of the wall. It opens when you get near. Easy?

A little 'Doom'-like exercise helps here. Jump across the crates - when you land on the last one, a slipgate opens. It will send you to the ceiling structure. Better shoot the... whatevers first! Jump back down to the tallest box, then you shouldn't loose any health. Jumping, i mean.

The first couple of crates will only exist at "Easy" setting. More experienced players have to aim for the doorframe. And be ready for an epic faceplant...
Thanks to Almos for this one!

...And when you get tired of _that_ particular stunt... Try a different jump!.
Mauritorami thinks that is easier. Thanks for the pic and suggestion!

Well, now you are up _here_... There is a secret room right over the entry gate. Jump down and get the warez, man.

When you walk up to this bone-shaped thing, a couple of doors open, and some nasty fellas start throwing garbage at you. Inside their boxes are big red switches, that opens the exit door. Push the small button on the middle of the 'bone', and you can enter one box to fetch a goodie.

Underneath the platform where you enter, a brick sticks out. It opens a room on the opposite side.

Use a cheat ("noclip") to get up here. In return, you will get a silly message. Great?

"And Now For Something Completely Different..."