Grimrock

I got to level 11 (the Tomb) and fought for a while, just to find the enemies there a bit hard for my party. Knowing that I had left some secrets behind (and probably the Boots of Valor) I decided to get back to the upper levels, thinking of killing some of those blue lizards that keep spawning in the northeast of the 8th floor. But... when I was leaving the final spiral hallway I found just a wall where usually there was a door. I remember kiting an ogre outside of that hallway before, so I'm guessing the door didn't just close because of a timer. Also, I recall coming back from level 9 once, with no problem, but I couldn't really assure it. Have I reached a point of no return where most of the game gets sealed away with all the treasures I didn't grab ;_;? Was it when I opened the prison door maybe?

If it's the spiral corridors I'm thinking of (where there were two ogres), there's a hidden button a few squares away from the end that will raise the wall for you again.