The Sector on the "Left"

Go into the 3D mode, point your cursor at the ceiling, and holding down the left mouse button move the ceiling down onto the floor then up 39 "Page Up's"

This will be your "Bottom" level or "Level 1" of your "Room over Room".

The Sector on the "Right"

Go into the 3D mode, point your cursor at the ceiling, and holding down the left mouse button move the ceiling down onto the floor then UP - 78 "Page Up's"

Now point your cursor at the floor and holding down the left mouse button move the floor UP - 39 "Page Up's"

This will be your "Top" level or "Level 2" of your "Room over Room"

NB.. be very carefull when counting the UP's here, as any mistake will cause havoc in your map.

Ok - so what have we here ? - Our ceiling of our Bottom/Level 1 is at the exact same "Z" axis as our floor in our Top/Level 2 - which is a very important requirement for Room over Room construction.

In both sectors go back to the 2D mode and draw an "inner" sector 1 grid square in and make it a "player" space (Alt S) as seen below.

Ok - lets give the walls and floor some textures.

The Bottom/Level 1 (Left)

I used Tile 16 for the walls and Tile 12 for both the floor sectors - The inner ceiling sector put the "Floor Mirror" Tile 341.

The Top/Level 2 (Right)

I used Tile 105 for the walls and Tile 18 for both the inner and outer ceiling sectors. The inner floor sector put the Floor Mirror Tile 341.

Back in the 2D mode - press the "G" key twice to get smaller grid squares.

Position 4 ST1 sprites in BOTH Top and Bottom Levels as seen below.

I have marked them 1,2,3 and 4

The Bottom/Level 1

ST1 (1) - Tag1 = 202 / Tag2 = 0

ST1 (2) - Tag1 = 110 / Tag2 = 2 / Tag4 = 512

ST1 (3) - Tag1 = 120 / Tag2 = 2

ST1 (4) - Tag1 = 110 / Tag2 = 2 / Tag4 = 512

The Top/Level 2

ST1 (1) - Tag1 = 203 / Tag2 = 1

ST1 (2) - Tag1 = 111 / Tag2 = 2 / Tag4 = 512

ST1 (3) - Tag1 = 121 / Tag2 = 2

ST1 (4) - Tag1 = 111 / Tag2 = 2 / Tag4 = 512

If you are not 100% sure your "Z" axis is correct - you can check it by doing the following.

What we need to do to accomplish this is to temporary join the two Levels, so in between the two levels insert 4 points as shown below.

Now BEFORE you join these points set yourself in the Bottom/Level 1 and go into the 3D mode - this tells Build which "Z" axis you want - now go back to the 2D mode and join these 4 points and you'll end up with a new "Player" sector as shown below.

Go into the 3D mode and standing in this new passage looking towards the Top/Level 2 - point your cursor to the ceiling of the passage (which will be the same height as the ceiling of your Bottom/Level 1) raise it UP - 1 "Page Up" - you should see a single gap appear between the ceiling of the passage and the floor of the Top/Level 2.

If this was the case - then all is well - if not CORRECT IT.

Ok we are almost done.

In the Top/Level 2 go into the 3D mode and if you now press the "3" key which takes you into the Room over Room mode, you'll be able to see your Bottom/Level 1.

The only problem now is your "Middle" walkway is to thin, so to make it more realistic press the "3" key again to get you out of the "Room over Room" mode.

Another word of caution..

Do not go into the 2D mode while the "Room over Room" mode is on.

In the Top/Level 2 place your cursor on the "Floor mirror" on the floor and move it DOWN - 4 "Page Down's"

Go into your Bottom/Level 1 and move the "Floor mirror" which is on the ceiling UP - 4 "Page Up's"

Now go into the "Room over Room" mode by pressing the "3" key and all will be ok. By pressing the "4" key, you can move between the two Levels.

Ok now you can get rid of the "Temporary" passage (if you created one) - Press "3" to get out of the "Room over Room" mode, go into the 2D mode, and place your "White" cursor in the "Passage"

Now press "Right Alt" - "Right Ctrl" and "Delete"

NB.. if you're doing this from Windows - the Right Alt, Ctrl Delete function will not work.

Ok - our Simple Room over Room is complete