Secret rooms are small areas which contain valuable items. These rooms are hidden behind make-shift walls which can be removed by shooting them down or using an explosive. Shooting the wall is recommended however as explosives are valuable. They usually contain useful items - exotic explosives such as Canguns or Meat-Traps, or in later levels more esoteric crafting equipment, such as Motors and Mchips.
Finding a Secret Room
Secret room entrance.
The best way to find a secret room is to walk next to walls. As shown in the picture to the right, a crack becomes visible where the wall is penetrable. This is a secret room. Another way to find secret room is to open your mini-map then spot out if some of the walls look thinner than all the other walls
In some cases, a crack may not be visible in the wall. If in doubt, check your map - it will show the destructible wall thinner than others.
Be just as cautious in a secret area as you would be anywhere else - although it is very rare to find a roaming enemy in a secret area, you can trigger ambushes from pipes.
Note: Don't be fooled by corridors that are blocked by boxes, they do not lead to secret rooms most of the time. If you look carefully you will notice that a box may look different or you can peer past the boxes, then it is mostly likely a secret room.
Best way to break the wall
Don't use your precious RDX explosives, instead use your AGL. In the new Teleglitch patch 9.3 it seems that Nailguns (and, in later stages of the game, Shotguns) are way more efficient way to break the walls. 2-3 shots is enough, The AGL have been nerfed if we talk about walls.