Thanks,
Yes the levels are built from a random assortment of prebuilt rooms, including special treasure rooms. They are joined together until the dungeon reaches a certain depth and then one last biscuit room is added. The rooms are of different sizes and there is some clever code to join the rooms together, including mirroring some of them for more variety
If you play enough you can learn the visual clues to to help go further.
Eg there is a room that has two paths either up or down. If you see a cobweb just before that, take the upper path otherwise take the lower. This helps you go deeper without backtracking, for higher scores.