Yorkhouse is the 139th level in Chip's Challenge 1. If you map the level out, it does indeed look like a castle with various "prisons" in it. This level is full of walkers trapped inside artificially created cells, which will be released when Chip takes the chips. Yorkhouse is not difficult, but tedious; there is plenty of wiggle room for Chip to move through if the walkers prove to be attacking him. All you must do is watch the road ahead.