It's been a few months since I started playing miniature games and RPGs solo, and so far I've tried a bunch of different systems and read many blogs (mostly Solo Nexus and other blogs linked from there) and discussion groups, all filled with great ideas. The goal of this post is to sort out my thoughts and experiences, specifically on playing miniature skirmish games solo.
The basic approach
The most basic way of playing a skirmish solo is to set up two "evenly matched" forces and play both of them the best way you can think of. You can play most skirmish games this way although some will require adaptation when they rely on hidden information (for instance, placing face-down order markers for each unit.) The problem with this approach is that it gets old fast, but it's still good to learn the rules of a new game. If you play this way, the main goal becomes observing how the battle turns out, rather than "winning" the match.
Uneven scenarios or "War isn't fair"
One step above the basic approach is the idea of setting up a scenario with a noticeable inbalance between forces. As you become familiar with a game system, you get a feeling for matchups that are unbalanced but interesting to play out. You still play both sides the best you can but now your goals will probably involve trying different strategies. How aggressive can the stronger force be without risking victory? How much damage the weaker force can cause before being defeated, or how long can they hold their ground? Even if you keep the "kill each other" goal for these scenarios, the uneven forces or the "unfairness" of the battle bring new questions to the table.
Often combined with the uneven forces approach, in this case the goal of defeating the whole enemy group gets replaced (or complemented) by something else. Common ideas include defending a region for some time, passing through a number of regions of the table, crossing the table from one edge to the opposite, stealing an item or rescuing a prisoner, eliminating or protecting one specific figure.
One problem with solo games, especially when playing both sides of a skirmish, is predictability. In my opinion, that's the main reason why solo players like activation rolls or card-based actvation systems. There is ample discussion on why such mechanics are good to model "fog of war" and uncertainty in the battle but in the end, making the game less predictable adds fun, in the absence of a human opponent. One approach consists in making a simple scenario with specific goals and then adding random events to "spice up" the game by adding new forces, ambushes and so on. Random events are usually checked at the end of each turn, or when specific values are rolled on dice during play.
At the top end of the scale in terms of sophistication are the systems involving autonomous behavior for the opposition. From what I've seen in games, the great advantage of autonomous behavior systems is allowing the player to focus on one force and play against the opposition, rather than ultimately taking the role of a neutral observer (when playing both sides.) As such, these systems have two main goals: reduce predictability and avoid the need for the player to make arbitrary decisions where he could (even subconsciously) favor his force in the game. Systems for autonomous behavior range from general guidelines on the behavior of enemy forces to decision tables for every possible action.
The role of narrative
Narrative has an important role in solo gaming. It adds meaning and purpose to the battles and it is yet another way to compensate for the lack of a human opponent. A basic "kill each other" solo game is made more interesting if you view it as the report of a historical battle (even if it's in the history of a fantasy world.) Adding description and features to miniatures (at least the leaders of each force) makes them feel more relevant than if they were generic troops. Making a character's tactical decisions based on their personal goals may also add variety to the game.
An extension of the use of narrative is the creation of campaigns of linked games involving the same group of characters. The appeal comes from the narrative interpretation of an ongoing story and empathy with the characters that are part of it. Since the player guides one of the forces through the campaing, autonomous behavior and random events are usually adopted for the opposition.
This is a summary of things I've learned so far regarding playing solo skirmish games. As a nice post in Solo Wargamer puts it, flexibility (in form, rules, goals and time) is possibly the greatest appeal of solo play.