Ron's Info-Closet Annex

Sun, 04 Apr 2004

Emption

Moratics is the study of generalised lines of strategy and tactics in games. For example, the concept of a tactical fork is common to Chess, Checkers, and many other games. I run a mailing list on the subject. My friend Chad Urso McDaniel attempted to revive discussion lately by writing,

Here's an assigment to help people get into the moratics mindset:

Choose any two distinctly different games you play over the next week and post to this list describing a gameplay strategy that you can employ in each. Try to find how this element can be used in each of the games.

My exercise involved two games from Seattle Cosmic last night, Starbase Jeff and Ad Acta.

In Starbase Jeff, "space station contractors" simultaneously play tiles in order to build a space station in the center of the table. Rules summary:

The contractor with the most money at the end wins.
The station starts as a few connected corridors. Some tiles simply extend a corridor, some make it branch, and "end caps" terminate corridors.
Tiles cost a certain base amount to build. This goes into a pot. You must also pay other players $1 for every tile they have between the tile you just played and another one of your tiles (you choose the route, and if you have no other tiles on the board, you pay only the base cost).
If you finish the station by capping the last corridor, you win the pot.
Every tile has a priority. End caps are in the range 0-2, while other tiles have priorities as high as 6 (the more branches, the more costly). The highest tile is Sabotage (7), which destroys one other tile.
Players take turns in descending priority. If two players play cards with the same priority, the cards "bounce" and are saved for the next round. If you have more than one card to play, you may play them in any order.

Dave Howell is a Starbase Jeff shark and won twice in a row against three of us newbies. At the end of the first game, he predicted correctly that I would play a 0 priority end cap and bounced with me, so we each had to save them for the next turn. On the next turn, he was the only player to play a 7 (Sabotage) card, so he went first. Since he could play his cards in any order, he played his end cap from the previous turn and won the pot.

The other game I played last night was Ad Acta. Rules summary:

Players score victory points by filing cards, or "files", in a series of filing cabinets. Every time a cabinet fills up, the cards in it are scored. The game ends either when someone has reached 36 victory points (in which case, she wins), or all cabinets are full, in which case the winner is the player with the most points.
Each filing cabinet has a number from I to VII. Each file has a letter from A to G and a colour that designates who it belongs to. There is also a series of icons along the top of each file that designates which player, or "office", must process the file next. When all of these icons are paperclipped, the file is "finished".
Some filing cabinets are better than others for certain files. For example, Cabinet II might score 7 points (the maximum) for a C file, while Cabinet III might score only 1 point for it (the minimum). Thus, timing is crucial. If you are "aiming" your C file for Cabinet II, you don't want to overshoot and end up placing the file in Cabinet III instead, scoring only 1 point instead of 7.
Each player has an in box and an out box. Tiles are processed from the top of your in box and placed in the top of your out box.
Each player has three action points that let him do things like process the top document in his in box or tell someone else to process the top document in her in box.
The first-player position rotates, and the first player in a round is called the Messenger. After everyone has had a turn, the Messenger places the contents of the out boxes into a delivery cart on the central board, preserving both the order of the files in the out boxes and the order of the out boxes starting with his own.
The Messenger then takes the top document in the cart (the last document processed by the last player). If it is complete (it has been processed by all necessary offices), he places it in the first available filing cabinet. If it is not complete, he sends it to the next office listed on the card, where it is placed on the top of the in box. He does this for each file until the cart is empty.

So, what strategic elements do these games have in common? Superficially, not much. One is about building a nonlinear map of a space station, the other about filing documents in a rigid linear order.

On closer examination, in both games it is important that you insert objects (tiles in Starbase Jeff, cards in Ad Acta) into the right positions in a "data structure" (a first-in first-out (FIFO) queue in Starbase Jeff, a last-in first-out (LIFO) stack in Ad Acta). Both games involve preemption tactics:

In Starbase Jeff, you can preempt another player's tile either by playing a higher tile, in which case you go before they do, or by playing the same value of tile, in which case their attempt to play a tile this turn is completely foiled (if someone else had played a 7 at the same time Dave did, he would not finished the space station and won that turn).
In Ad Acta, you can preempt someone's attempt to get a card into a given filing cabinet by making sure that there are enough completed files after his file in the turn order that they will end up higher in the delivery cart and will go into that cabinet first. For example, it is useful to preempt someone's file with your own if getting your file into that cabinet will score you lots of points, or if the cabinet in question would score your opponent lots of points.

A related concept is what I will call postemption. Sometimes you want other people to go ahead of you.

This might happen in a two-player game of Starbase Jeff when there are two branches left on the space station, and you are fairly sure your opponent will play an end cap. You could try to "sneak in" an end cap with lower priority so that your opponent caps a corridor first, leaving you to cap the remaining corridor and win the pot.
Postemption in Ad Acta might take the form of trying to get into a later file cabinet that is valuable to you by completing one of your files earlier in the turn order.

Or consider Hearts: in Hearts, the cards played in a trick have a notional order: the highest Heart card wins the trick, unless there are no Heart cards, in which case the highest card of the suit led wins. The player with the lead is the person who took the last trick. Sometimes you want to lead, because it gives you better control, so you might preempt the other cards with a higher one. However, if a trick has a lot of Hearts in it, winning it will cost you, so you should generally try to postempt it by "sneaking in" a low card.

Thus, preemption is a somewhat more general version of the concept of trumping, and postemption is its complement. I suggest the backformation of emption for the general concept of inserting a card, tile, or other game object into the right place in an ordered set, to your own advantage.

Note: You can follow this thread from its beginning in the moratics archives, which are open to the public.

Entered 19:52 [/games/moratics] permalink

Ron's Info-Closet Annex

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Sun, 04 Apr 2004

Emption