2 2
2 / /
/ +---+---+
+ | o
/| + +
+ + /| 2
| v | /
+--+ 1 +--+
| |
+--o+ +-o+---+---+
/ | /
v +-=--+ /
4 / | | /
+---+ +--+
o
+
1 = Mega-Maze Basement (Part 1)
2 = Mega-Maze Basement (Part 2)
4 = Mega-Maze Basement (Part 4)
Here is the universal key.