This is Dark World (Mattel, 1992), the classic dungeon crawl adventure game for 2-5 players. It is missing 1 of the 2 EXTRA plugs to affix the castle to the board (there is still 1 extra). It is otherwise complete.

The box has fairly heavy wear, but is very sound structurally. One of the wall sections is taped underneath the location of the secret door (which is currently unattached, and looks like a pain to put in place). Aside from that, everything appears to be in very good condition, with the normal reasonable wear to be expected from a cardboard assembly/disassembly routine.