LOTS OF BUILDINGS
Small errors may creep in if you place a large number of buildings. In particular, the "building site" building is prone to partial collapse when the game starts up. This doesn't effect the structural integrity of the building, and because it occurs while Mike is flying in over the city, doesn't trigger the countdown timer. However, vacuuming up the fallen parts WILL start the timer.
The two buildings on the left show start-up damage; the one on the right is intact.

Placing two signs on the same side of a building also seems to trigger a partial collapse when the limit is reached. This one will trigger the start timer.

These glitches seem to have a definite tipping point: they won't effect the same items placed before that limit is reached.

BUILDING ON BRIDGES
You can, is the short answer. Bridges can be placed over canals, and you can build on them. You can place green islands over these buildings: the ground won't turn green on a bridge once the buildings are destroyed, but any trees you've placed will sprout.

BuildingGlass1x12Type2
This is the tallest building in the game. Under certain circumstances - not entirely sure what they are, but it could be exceeding the "safe" limits of the game engine - these buildings will lean, or even spontaneously collapse.
The "leaning" is most noticeable when they're placed next to each other.
Did anyone order a tower on the side?

GAS TRUCKS
Gas trucks parked on the boundaries of the world can't be selected if the player is using the Car Controller. This effects trucks parked parallel, within two spaces; or at right angles within one space. The screenshot below shows which trucks can be used and which can't.

Trucks parked in the × positions can be launched using the radio controller.

This glitch does not effect cars or vans.

VANS
If you're going to have a problem with a moving vehicle hitting something, it's most likely going to be a van that's the culprit - especially when it's turning a corner. Gas trucks tend to get impatient and run into cars, but vans are the sneaky ones.

SOME PARKED GAS TRUCKS AND VANS EXPLODE WHEN THE GAME STARTS, AND/OR SOME PARKED CARS EXPLODE WHEN I TRY TO USE THE CAR CONTROLLER ON THEM
This one really threw me. Turns out the game engine has some kind of a "limit of wheels". When you have too many vehicles on the map, they sink up to their axles in the surface when the game starts. (Note: they look perfectly normal when you're in edit mode.)
This is enough to kill vans and gas trucks immediately, but cars will survive until you try to move them. Like the building/object errors, this only effects vehicles placed after the limit is reached. The solution is to reduce the number of vehicles. (You'll probably have to replace the effected vehicles if you want to keep them in the game.)

VEHICLES ON A PATH RUN THROUGH ONCE AND DISAPPEAR
If a path enters or exits "through" a tunnel in a platform, and one or both of the outside tracks empty of vehicles, the culprit is the tunnel. The tunnel uprights are solid and intrude onto the driving space. My solution is to insert a curve point in the track a little ahead of the tunnel, then switch off "Snap" and move the terminal point of the path inwards a bit, so that vehicles - particularly vans - can get past the tunnel entry/exit without damage.

Alternatively, widen the tunnel. It may be less aesthetically pleasing to have tunnel lanes with no roads, but it solves the problem.

VEHICLES ON A PATH QUEUE UP BEHIND A NON-MOVING VEHICLE
Vehicles move, then get stuck? Can you select the lead vehicle with the the Car Controller and drive it off? You've selected "Parking" accidentally, before placing the vehicle on the path. Delete the stationery vehicle(s) and replace them with "OnPath" vehicles.

VEHICLES ON A PATH DON'T MOVE AT ALL
If you can select them with the Car Controller and drive them away, all the vehicles are "Parking" vehicles. Delete them and replace with "OnPath" vehicles.

If they explode when you try to drive them away, you've exceeded the number of vehicles the game engine can cope with (see above).

VEHICLES ARE JUMPING TO A CROSS ROUTE WHERE I DON'T WANT THEM
I found this out when I tried to create a route that looped back on itself before continuing on. The cars got stuck permanently on the loop. I don't know how vehicles choose what path to take when lines cross or come close; but the solution is to avoid crossing paths wherever possible; and to make sure that parallel paths are not too close together.

VEHICLES ARE DRIVING WHERE I DON'T WANT THEM
This has three possible causes:

• You've selected a vehicle "OnPath" and placed it off path. At the start of the game it will attempt to connect to the closest path.
  
• A vehicle is facing the wrong direction on the path. This is most likely because you've reversed the direction of the curve after placing the vehicle. The vehicle will attempt to do a U-turn. It might then get "hijacked" by another path if it gets closer to that than the original path during the U-turn.
  
• A vehicle started on one path but is now running on another. If an "OnPath" vehicle's route is blocked (by debris, for example), it will attempt to drive around it. If it crosses another path in the process, it will attach itself to that path.

HOW CAN I MERGE TRAFFIC?
The simple answer is that you can't. Not safely. Even if you spent a couple of hours carefully placing vehicles so that two paths could use the same stretch of road by merging, the inevitable hold-ups will create chaos in a matter of seconds. The game has a braking mechanism to try and avoid collisions, but it's an inexact science.

You can have two paths travelling on the same lane without accidents, provided you place them far enough apart.

Generally best to stick to cars if you do, though: gas trucks need more room to turn, and vans are bullies that will hit anything.

Remember that vehicles trying to drive around blockages will attach to another path if they cross it.

An alternative to doubling-up is to create an additional lane or, if they're only sharing for a short distance (as in the screenshots above, where the car on the left is about to turn down the side road), add a slip lane.

ALL THE VEHICLES HAVE GONE FROM THE CAR PARK, BUT THE 'PARKING BOY' MISSION WON'T COMPLETE
The Parking Boy mission is linked to a selected area. First off, all the damaged car debris has to be removed before the mission will complete, but you probably know that if you've played the game.

If any vehicle is within the selected area, the mission can't complete. On big maps with lots of buildings, this may include moving vehicles.

Either reduce the boundary of the selected area so that it doesn't intrude on the roadway, or wait: the inevitable blocked routes as you get on with demolition will free up the space eventually. Just don't kill the Parking Boy in the meantime!

I'VE RUN OUT OF VEHICLES TO PLAY WITH!
Vehicles travelling on an open path will regenerate throughout the game, provided the debris is cleared up. Parked vehicles, and vehicles travelling on looped paths, do not regenerate after they've been destroyed.

VEHICLES AREN'T STOPPING AT TRAFFIC LIGHTS OR PEDESTRIAN CROSSINGS!
That's right. It was too complicated to include the functioning traffic lights in the editor, so they (and the pedestrian crossings) are purely decorative. And vehicles in the game don't stop at pedestrian crossings anyway.

I SPENT AGES SELECTING EXACTLY THE VANS/CAR COLOURS/PEDESTRIANS* I WANTED, AND THE GAME MUCKED THEM UP!
Yeah. The van signage, car colour or pedestrians* are generated randomly each time. I know that the game itself has dedicated little old ladies trying to cross the street, but you don't have access to a pedestrian crossing mission, either.

(* You can, of course, select cowboys, business men and construction workers specifically. Only pedestrians chosen using the "Pedestrians" button are effected - and that includes all the little old ladies.)

OBJECTS ARE FALLING OVER OR COLLAPSING WHEN THE GAME STARTS!
I know that this effects piles of pipes and single fence panels, at least. (It also effects the Building Site building - see the "Buildings" section of this guide.)
Collapsing pipes contained by road barriers for aesthetic effect.

The level you're creating has exceeded "safe limits". This error only effects those objects placed after that limit is reached. I don't know what the specific limit is.

SAND
Sand piles don't effect some things. You can put several piles together, or bury (non-destructible) stuff in it if you want.
The sand won't trigger the dodgy digger.

GAS STATIONS - PARKING VEHICLES BY THE PUMPS
You can place vehicles under the gas station roof, but it's a multi-step process.

• Place the roof (or roofs) where you want them
  
• Install the gas pumps, which will slot in under the roof.
  
• Vehicles, however, won't - even holding down the CTRL key.

• Place a "Street Line 1x3" decal under the roof. You'll probably need to turn off "Snap". You'll find that the middle line is a perfect fit between the uprights of the roof.
  
• Select all the items you've just placed. De-select the three-line road decal by holding down the Shift key and clicking on it.
  
• Move the assembly out of the way.

• Place your vehicles using the central line of the three-line decal as your guide. If you're using four pumps, two will fall along the line; the other two beyond the ends. Remember to leave enough of a gap for the pumps to fit back into the space.
  
• Re-select the roof/pump assembly and place it back into position, using the central white line as your guide. Multiple types of objects in one selection will not snap into place, so you'll have to place them carefully.
  
• Select the white line decal and delete it.

Voilà!

[SHIPPING] CONTAINERS
Nothing about these particularly, but they're fun to stack and even more fun to destroy. Consider this my attempt to encourage their profligate use. :)

TRYING TO PLACE ANY KIND OF OBJECT: THE CURSOR'S THERE, BUT THE OBJECT ISN'T
Turn off "Snap to Path" in the Move menu.

"Snap to Path" effects everything, not just vehicles - and it doesn't matter how far away on the map the path is.

THE PYRAMID LEVEL BARRIER IS POINTING UPWARDS RATHER THAN IN
This happened to me with my first attempt at creating a level. I'd selected the pyramid to move it, and the next thing I knew it was pointing up. Flying around in-game, the level barrier was forming a roof - not effecting gameplay, but visually annoying.

I have no idea how this happened, but my PC has Tourette's, and is prone to frequent random ticks. It's most likely that this happened just as I went to move the level barrier.

If it ever happens to you, e-mail support and ask nicely, they may be prepared to fix it for you.

(Sorry, I don't have a screencap of this one, and I'm not about to try and do it again.)

TRYING TO PUBLISH A LEVEL, BUT GETTING THE ERROR MESSAGE "Code 9 filenotfound"
This occurs if you've previously uploaded the level, then deleted it. (Tip: don't delete the old file: hide it if you must, then re-publish the corrected version.)

I found the solution to this in the "Discussion" page when it happened to me, but for convenience I'll repost it here:

• Go to My Documents\DemolitionInc\[your steam user ID]\customLevels
  
• Look for the most recently changed xml file - it should be the level you're trying to publish
  
• Open it in notepad (right-click -> open with -> notepad)
  
• Look for the line that starts with <LongName> - it should be the name you expect. If not, check other files in the customLevel folder
  
• Look for the line that starts <PublishedFileID>, and delete it.
  
• Save the file and try and publish again.

Did as it said, saved the file, uploaded the revised version with no problems.

THINGS OTHER PEOPLE'S UPLOADED LEVELS HAVE TAUGHT ME

I'VE DESTROYED EVERYTHING BUT THE GAME WON'T FINISH!
There must be at least one building in the level, within the level boundary. The timer stops and the game ends when the last (or only) building within the boundary is destroyed.

THERE ARE ALL THESE BUILDINGS TO DESTROY, BUT THEY'RE OUTSIDE THE GAME BOUNDARY!
There are two basic types of building in the game: destroyable buildings (found under "Buildings" in the Create menu), and background buildings (found under "Platform" and "Background"). There are three distinct differences: in edit mode the background buildings come in pre-assembled cityscape sets; and in play mode background buldings do not have glowing bases and cannot be destroyed.

Placing destructible buildings outside the game boundary is really confusing for the player: they can be destroyed, and will earn dollars; but they can only be destroyed "accidentally" when a vehicle overruns the boundary, they waste precious resources when you try to aim for them; and most importantly, they are not counted in the "buildings to be destroyed" total.

All up, destroyable buildings placed outside the boundaries are confusing, largely pointless, and bloody annoying. Please don't do it.

(If you feel like you have to place destructible buildings outside the area you've set for yourself, move the boundaries back.)

HELP! I CAN'T STEER A CAR SUCCESSFULLY THROUGH A TIGHT MAZE!
Neither can I. You're on your own with that one.

• Watching long chains of buildings topple thanks to well-placed explosives is fun, but don't forget that the timer is still ticking.
  
• Before you destroy that radio control transmitter, make sure you know where the receiver is.
  
• Destroying huge stacks of shipping containers is not completely pointless - it does earn cash - and it's great fun! ^__^
  
• The Mission Reward dollars you earn for completing a user-created level are not added to your player total - only the in-game levels do that. What the reward dollars do in user-created levels is drive up the finishing total; which in turn has an effect on the Rank Scores star rating system (whether you earn one star, two stars or three stars on completion). If you're creating a level with a $4 500 000 reward, take that into account when you're setting the levels at which the three- and two- star levels kick in [shown as 0 and 1 in the Setup/Rank Scores menu]. In the end, setting a big reward really just means that you're going to be spending a lot of time with your finger pushing down on the mouse button.

There are some issues with the Editor: some are deliberate [the traffic lights don't work]; some are limitations of the game engine [you can only have so many vehicles on a level]; and some are being looked at. The glitches below are listed for information: they have been reported to Zero Scale.

Several of these are discussed in more detail elsewhere in this guide.

THE EDITOR SCREEN IS REALLY DARK!
Yes. Yes it is. This is a rendering error, and is being investigated. The biggest challenges are placing tyre mark decals and, oddly, pedestrian crossing decals. Oh, and generating thumbnails.

I MOVED A RADIO CONTROL RECEIVER AND NOW IT ISN'T WORKING!
It is working, but it's working in the place where you originally put it. The game hasn't un-linked it, so it ignores the new location.

VEHICLES ARE EXPLODING WHEN THE GAME STARTS OR I TRY TO DRIVE THEM!
You've exceeded the number of vehicles available for use on a level.

THINGS FALL OVER WHEN THE GAME STARTS!
You've got a lot of stuff on the level, and have exceeded the comfortable limits of the game engine. So long as the Army Timer isn't triggered as soon as the game starts, it's not usually an issue.

MY TALL BUILDINGS START LEANING WHEN THE GAME STARTS!
This happens to BuildingGlass1x12Type2 when you have a lot of buildings in your scenario, or when you have a lot of BuildingGlass1x12Type2, or just because it wants to. Sometimes they fall over of their own accord. It might damage the purity of your design, but it adds to the fun.

I'M TRYING TO PLACE SOMETHING IN THE EDITOR, BUT IT'S NOT THERE!
Yes it is. Turn off "Snap to Path" in the "Move" menu.

PLAYERS CAN'T SELECT GAS TRUCKS USING THE CAR CONTROLLER!
Move them away from the boundaries of the map. See under the "Vehicle Behaviour" section of this guide.

THE PARKING BOY MISSION WON'T COMPLETE!
Re-scale the mission boundary so that it doesn't encroach on roadways. See under the "Vehicle Behaviour" section of this guide.

I GET A 'CODE9' ERROR WHEN I'M TRYING TO PUBLISH MY LEVEL!
See under the "Miscellanea" section of this guide.

I CAN'T GET CARS TO SIT UNDER THE GAS STATION ROOF!
There's a tutorial in the "Objects" section of this guide.

MY VEHICLES ARE DISAPPEARING OFF THE MAP AND NOT COMING BACK!
Parked vehicles, and vehicles travelling on a closed path, are not regenerated when they're destroyed. Vehicles on open paths will only be regenerated when the debris from the destroyed vehicle is cleared. Vehicles travelling on the outside lanes into or out of a tunnel are prone to hitting the upright of the tunnel - and the destroyed vehicle sits in hyperspace blocking everything in that lane from regenerating. See under the "Vehicle Behaviour" section of this guide for a couple of fixes.

I'VE PUT VEHICLES ON A PATH BUT THEY'RE NOT MOVING!
You selected "Parking" mode vehicles. Delete them and replace with "OnPath" vehicles.

MY VEHICLES AREN'T TRAVELLING WHERE I WANT THEM TO!
See under the "Vehicle Behaviour" section of this guide.

I SELECTED A REALLY FAST VEHICLE SPEED, BUT THEY'RE STILL GOING SLOW!
The more stuff you have on a map, the harder the game engine and your computer have to work. This results in loss of performance.

IT TAKES AGES FOR A MENU CLICK TO WORK!
You have a lot of buildings on your map. If they're not your immediate focus, go into the "Layers" menu and de-select "Buildings". Things will speed up immediately, I promise.

If you need to work with buildings, or just want to do something really quickly, zoom in as close as you can - that'll help, too.

MY THUMBNAILS HAVE UNWANTED ARTEFACTS ON THEM!
Mine, too. Like me, you probably have a big map with a lot of buildings on it, and the game engine and/or your computer is struggling to cope.

I'M TRYING TO REPLACE THE THUMBNAIL ON MY LEVEL WITH A SCREENSHOT. I'VE RE-SIZED IT AND RE-NAMED IT AND EVERYTHING, BUT IT'S CORRUPTING WHEN IT APPEARS IN THE MENU!
Me too. Let me know if you find a solution.

Thanks to short$ale and Eyes for their forum discussion regarding the "Code 9" uploading error, which saved me a lot of heartache. The pertinent details have been reproduced here in the "Miscellanea" section for easy reference.

Thanks to the guys for the you-beaut tutorial video: it was really easy to follow and very useful. Having a copy of christ's User Guide on my desk helped a lot in the early stages, too.

Thanks to Zero Scale for sticking with Demolition Inc. and bringing out more DLC and the editor - like I didn't already have enough to procrastinate with! Demolition Inc. has been my "go to" game since I first bought it: it loads fast, it's huge fun, and I can play as long or as short as I want and still have a satisfying experience.

Above all, thanks to christ on the Zero Scale helpdesk, who sorted out a lot of problems for me early on with patience and encouragement - even the stupid stuff.

Finally, though, thanks to me for figuring out, after 115 hours of gameplay, that I didn't have to view it in 320 x 200 resolution. >_<