Grimrock

They do NOT respawn...there are just lots of them and there are also secret rooms that open without you knowing it that have spiders in them. Open the door and run away. They will chase you. Get far enough away and they will lose interest. Then sneak in and hunt them down one at a time. Run back to the Healing Crystal often. Save often. Rest often. Hide often. It is possible. I and many others have cleared it on Hard setting.

you can lure the spiders to the rotating teleport room wait untile it gets teleported go backwards where the spider came and wait until its in the middle of the room and take the stone away from floor controll to drop it....easier to kill but can be done =D