The single most important goal of the new COIN bot designs is usability. There are many places where small changes have been made to enhance usability, but the primary change (and a large one!) is the division of the operation selection and space selection priorities into different charts. Trưng divides these using the same principles as the Arjuna bot in Gandhi: operation selection is now handled by a deck of cards, while space selection is handled by the priorities charts that were previewed in the last article.

This division gives much more granularity to the space selection and allows for space selections to be tied to different player actions (placing pieces, shifting opposition, or moving pieces, for example) rather than specific operations. This allows the bot to execute Event cards more efficiently, but also makes it easier to break each action down. To demonstrate, let’s take a look at the first NVA turn of the Medium Scenario in a playtest game I recently completed. Before we start, this is about the most complex turn that I could find in my entire game, so it should help you to understand what the Solitaire system really looks like in action.

The very first card of the game is #41 Bombing Pause, which has the NVA as first eligible. Because they were written for the old solitaire system, Trưng does not use the Solitaire symbols on the card to determine whether or not it will play the card. Instead Trưng has a separate chart which determines if an event is Critical, Effective, or whether the bot ignores the events entirely. Bombing Pause is Effective for NVA, which means the NVA will execute the Event but not at the cost of skipping an Operation and Special Activity. However, Bombing Pause adds Patronage, which makes it a Critical event for the second eligible faction (ARVN). So, NVA will select an Operation Only to deny ARVN access to the Critical event. This is a change from how previous bots worked, and simulates more human-like play.

To select their Operation, the NVA bot reveals cards from the Trưng deck until an NVA card is revealed. The NVA get card P. When resolving a Trưng card, start at the top of the card and check each blue box – if the condition is true, follow the green arrow; if the condition is false, follow the red arrow. The first blue box on card P (see illustration below) asks if COIN Controlled Population and Patronage (the ARVN Victory Condition) is at last 42 – is begins the game at 44, so we follow the green arrow to the next blue box. This box asks if more than 20 NVA Troops are on the map; the NVA have 18 Troops on the map at the start of the medium scenario, so we follow the red arrow to the ‘flip this card’ icon. So, we flip the card over to side PP.

The blue box on the backside of the card asks if two six-sided die rolls added together (“2d6”) are less than or equal to the number of Available NVA Guerillas, or if that is false, if “1d3” (this term is explained in a moment) is greater than or equal to the Trail (which starts at 3). There are 4 Guerillas, so nearly every roll will end up failing this test – and in our case we roll double 4s. Because the first check failed, we check if “1d3” is greater than or equal to the Trail. 1D3 is a six sided die roll where 1 and 2 count as a 1, 3 and 4 count as a 2, and 5 and 6 count as a 3 (in other words, roll a die and halve it, rounding up). So, unless we roll a 5 or 6, this will also be false. We roll a 2, and follow the red arrow.

The next box is a Special Activity (Infiltrate), and the NVA is executing an Operation only, so we skip this box entirely, and go to the following box. That is an NVA March. NVA March has a bit of a reputation of being difficult to perform using the NVA bot that came with Fire in the Lake, and is quite a bit different when executed with Trưng (whether it is easier, I leave to your judgement). The box contains two instructions: March according to the Move Priorities, and select destination spaces using the March Destinations column of the NVA Space Selection table.

To execute an NVA March, first we consult the Move Priorities chart (a portion of which is pictured below). It tells us to select a destination space using the March Destinations column. Since there is no COIN Control in Laos or Cambodia, and the Trail is at 3, we will select a space adjacent to the most NVA Troops that are yet to March (at the end of this article I’ll talk about what happens when the Trail is 4). Quang Tri is adjacent to every NVA Troop on the map, so we’ll select Quang Tri as the destination and go back to the Move Priorities chart, which instructs us to select a origin for the March – the space with the most NVA pieces that are allowed to move (e.g. have not Marched already) and adjacent to Quang Tri.

Both North Vietnam and Central Laos have 10 NVA pieces that can move, so we select between them randomly. Assigning probabilities and rolling, we select North Vietnam as the origin. So, we March from North Vietnam to Quang Tri. The Move Priorities chart summarizes some rules for Marching – NVA will never move pieces out of a space if it changes Control, and will always keep an underground Guerrilla at an NVA Base. NVA will also keep 3 Guerillas in a space if it has room for an Available Base, and keep Guerrillas on LoCs so they exceed all enemies.

To determine how many Troops or Guerrillas to move, we consult the next section of the Move Priorities chart, shown below, following the red NVA column from top to bottom. Unlike the Space Selection Priorities table, here each dot provides an instruction for the moving pieces. Since the destination space is a Province, we can skip the first dot that only applies when Marching onto a LoC. First, we check if 2d6 is less than or equal to the number of NVA Troops in North Vietnam plus the NVA Troops already in Quang Tri – we roll 2 and 3, so we move max Troops. In our case, this is all 9 of them! Since that’s all the eligible pieces to move from North Vietnam (we must keep 1 underground Guerrilla at a NVA Base), we check if we select another origin space to March into Quang Tri, or if we are finished Marching into Quang Tri. Since we now have NVA Control in Quang Tri, we will move onto our next March Destination. But first, we roll against the Activation Number on the NVA card (the die in the top right corner) to see if we continue the Operation or if we are finished. The Trưng bots do not use Resources; instead the Activation Number regulates the number of actions the bot can take.

The Activation Number on this card is 2, so as long as we roll higher than this number, the NVA will continue the Operation. The NVA rolls a 6, and continues on to select the next space using the March Destinations column… and this is where our example stops.

So, what if the Trail had been at 4? You may recall this permits the NVA to March pieces into Laos and Cambodia spaces, then continue to march those pieces in a further March operation. In fact, much of the complexity of the NVA March comes from this case (in addition, NVA March in and out of Laos/Cambodia is free when the Trail is 4). This offers immense flexibility to the NVA during their March Operations. To handle this complexity, Trưng simply treats every Laos and Cambodia space as adjacent to each other and every adjacent space when the Trail is 4. This means pieces can March directly from The Parrot’s Beak to Quang Tri when the Trail is 4 without all the intermediate movements; this move would be possible in the regular game, but as each space may only be selected as a March destination once, it would take a large amount of extra logic to enable Trưng to handle these Marches. So, a small rules exception allows the same effect.

Hopefully this gives a big-to-small picture view of how Trưng works and how it feels to play Fire in the Lake with this new Solitaire system. So far, our playtesters have loved playing with Trưng (I know I have) and we look forward to you trying it out as well in the very near future.

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Previous Articles:

A Sneak Peek at Tru’ng: The New Fire in the Lake Bot System

Design Diary: How and Why We Are Evolving the Fire in the Lake Bot System