The cage of glass can be solve by:
1) Using the knife or the key to scratch the glass.
2) After scratching the glass, Kick the glass.
If you don't have the knife or the key, then evaluate the places were you already used them, maybe there are different ways to solve those situations? There is a path that will work for every game. The order of encounters is random, but every player always sees the same set of encounters therefore the game is always solvable with the right choices.