 Enemy monsters inhabit the levels , but the player can crush them by flattening impassable blocks against them . The player may also encounter timers in the form of alarm clocks that will begin to elapse when crushed for the first time and can only be stopped when Danny jumps on them . Danny wakes from his mental explorations if he falls off the level or too high of a surface , is touched by a monster , or fails to stop a timer , but the C.R.U.S.H. device reinserts him at the start of the level or the last checkpoint Danny passed . 
