The secret panel is only opened when the user goes up to the wall and pushes on the wall. In the holodeck this action could be fed from a glove worn with the helmet or a switch held on either hand. Doom also has places where secret switches and levers have to be found and operated before entry into optional areas of the game is permitted as shown in figure 7. Sometimes these are compulsory and players can spend hours hunting for these switches and panels. Sometimes in a similar game to Doom called Duke Nukem 3D, there are arrays of such switches and they have to be operated in a correct sequence to have any effect.
Players can spend time working out combinations of switches that set off events.
Duke Nukem 3D also has switches which cannot be reached by hands - you need to point a gun and shoot them. This is another feature that could be incorporated into the holodeck if there is feedback from weapons. To make weapons very selective, they could have an infrared detector. The gun must be aimed at an infrared source in the holodeck for it to activate correctly. Interesting places to hide weapons, switches, maps and boots.