For those wondering how the level generation is done, here is an explanation I found while watching Game Maker's Tool Kit:
There is a 4*4 grid, and a random tile on the top of that grid is chosen as the starting location(X = START):
X
Then, the game decides which direction to go in(left, or right), and after that, chooses to march in that direction or go down. If the direction it moves in would cause it to fall off the grid, then it chooses to go down. If it tries to go down at the bottom of the grid, then it plants the end location(X = START, O=Part of path, D=DOWN,F=FINISH):
DX
OOD
DO
FO
This(usually) generates a path that dosen't require bombs or ropes. The rest of the rooms become side rooms, that either are accessible via openings without bombs, or closed off requiring bombs.
After that, a random room is decided to link the rooms together. So if there is a room where the next tile drops but the previous tile said to go left, then it will pick a pre-created room that has the exit tags 'right'(since we came from the left) and down. It can also generate an additional exit if the room at least connect the previous two grids, so that the player can reach an optional room(which may be a dead end with nothing of value).
After that, the "props" are added, such as enemies, cobwebs, crates and chests, deciding what blocks to make gold or pushable, placing random blocks in certain areas, etc. Loot and enemies usually spawn in cramped spaces, but also spawn elsewhere. Trees, springs and tiki spike traps are also added during this, if they weren't part of the current grid generation by default and the world is appropriate.
