You have a few options. Random decks, constructed decks, planned decks and structured decks.
A random deck is simply a bunch of theme related cards thrown in with some common cards and off you go. You might want to put a few cards at the bottom of the deck that are the target of the evenings adventures.
Constructed decks are where you specifically select the cards used, based on a theme or story line. This can be combined with a planned deck.
A planned deck is one where you place the cards in a specific order, or bunches of them in specific order and placed at specific locations within the deck. You get to control the adventure quite tightly – some might call this railroading your players, and they are probably right. There are times when this makes sense though.
A structured deck is probably better then a planned deck. In this deck you have a few small blocks of cards they are placed in order, and then specifically placed within the deck at certain points. But between those cards other cards are placed randomly. This is particularly useful in larger decks, decks with large structures consisting of several cards that should be linked together etc.
An excellent option is to place all or some of the cards face down on the table. The players may have a map already that gives them some idea of where everything is and this option allows you to give them some advantage, plus some idea of what they might be getting into. Feel free to add secret doors and maybe a whole extra deck of things they don’t know about but can select from as optional content.
Where you have an adventure with a structure that dominates the deck, such as the main building in the Necropolis deck, you might want to start with several cards laid out for all to see. The players will be responsible for connecting the ENTRY card to the pre-laid structure – tell them this.
Another option is a limited play area. Create an enclosed area and tell the players that all cards must be laid within that area. This helps to keep the layout compact, a good idea where you don’t have much table space. You can have unusually shaped areas (like a big hollow cross) that can act as guides to create a certain shape relevant to the areas purpose or meaning.
Linking & Levels
The Sky Scraper is an obvious deck that implies levels, floor after floor after floor. But your story is most likely not interested in all of the floors, just a few that the players have to get through before they get to the end of their journey. IN the Sky Scraper deck the rooms/apartments/penthouse are linked by stairs and lifts, these tiles reflect to multi-level nature of the deck. When you construct the deck you might want to include extra stairs, and construct the flow of your deck such that stairs lead to a room, leads to a stairs, leads to a room etc.
Forced & Held Cards.
If your story requires that a specific card only appear at a specific time or place, then hold the card back. Don’t put it in the deck. Keep it in your mean, nasty, conniving GM Hand and play it at the appropriate time and place.
If by some oversight or accident a card appears that you don’t want to use at this time then another option to create some reason why they cannot enter it. They can see it, but some kind of barrier prevents them getting onto the card.
To avoid confusion you probably want to not allow cards to overlap. There really isn’t any reason to do this, even in a multi-level structure the floors can be fanned out over the table top, linked by stairs to represent the 3D structure.
Usually I would be playing with cards placed so that they run edge to edge. Because cards are oblong in shape you will have the short side of the card running along the long side of another card, this is ok. In fact I recommend that Common cards are played short to wide or wide to short to enhance the visual of longer transit from one room to the next.
Do not be locked into rigid placement or rigid contact rules. Allow the cards to spread a little so you can get a structure that works rather than one that is 5mm short. Proximity is all that is required.
There is a vast array of extra cards you could include in any of these decks. A ledge card could be added to the Sky Scraper if your story required the players to venture out onto a dangerous ledge many stories up. Making new cards and adding them to your deck is simply a matter of cutting out a piece of paper 3.5x2.5 inches and writing your idea on it in big letters.
There is a temptation to add details to your cards, such as an encounter roll, a chance of random events, even a creature encounter table. I suggest against doing this. This sort of information should be kept in the GMs notes and revealed to the players as required. This gives you maximum flexibility in your options to respond to cards not falling in ideal patterns.
If you are rushed and quickly throw a deck together, only for the players to draw out an unexpected result that seems to be undermining your carefully (but quickly created) plans then fess up. Before they play the card take it back and shove it back into the deck down toward the bottom. Everyone wants to have a full adventure, everyone will live with it. Just be honest, you’re only human.
The Cards are simple suggestions, their name evokes a specific image in everyone minds, just be sure everyone has the same image.
You can help make sure everyone is on the same playing field by having a short descriptive sentence about the card, and even a set of descriptive aspects that can be applied and used by everyone (looks at FATE, but there is no reason other systems cannot use this idea).
I hope to put out an set of aspect tiles for use with the cards that can be placed on the cards to visually show their details (see above however).
An example of play.
The below is an example of Mapping Cards in play. I have used the Dragon’s Lair deck as the basis for the adventure and added some Common Cards to fill out the deck a bit. In total there were about 52 cards.
The Dragon’s Lair adventure gives you 5 sub-sets of cards representing the entrance and four specific lairs. At the bottom of the picture above you can see the entrance area, the first card turned up. Around the outside of the center block are the 4 major encounters of the pack. I added another area in the center initially, but by the time of the final game I changed this to 4 separate cards with special treasures spread around the main area as shown in the below shot.
Treasures are indicated by the small chests placed on the cards, this gave the players a visual clue about where to go. They were told that the outside lairs were dangerous, and to explore a bit inside to start.
The drawn box was the play area for randomly drawn cards. A deck of about 50 cards was used and players could draw 2 cards each move. They had to place one of the cards to explore the dungeon. Some of the cards were events and were added to the card they played, so Trap cards were played with a room/corridor card.
Direction was limited to one of the sides of the existing cards, to create a formal grid, but the cards can be played long or short side touching, as you can see in the following pictures.
This picture shows play after they had passed all the entry area and made it to the centre of the play area for their first treasure chest. Note the use of corridor cards that forced them to detour off a straight line.
In this picture they had travelled to one of the corner cards to gain a second treasure chest. Note how they have now started using the long sides of cards to get there quicker (with less cards).
In this last picture (flipped to the other side for this shot), you can see they have crossed the play area and made their way into one of the outside lairs, confronting the demon there and gaining the 3 treasure chests.
For this adventure I rolled for random encounters at 1in6 for each card drawn. I had a list of 6 creatures that would be used for the random encounters. They could be re-used if required.
I also did up a list of 20 descriptive effects that could be applied to the cards randomly as they entered them. Things like variable lighting, webs, ruined statues, vegetation etc.
These random tables are very useful for quickly adding atmosphere to the cards.