I really like this game and plan to continue playing it solitaire, however, one thing I can never wrap my mind around is playing solo with op-fire. How do those of you who play this game solo decide when to activate op-fire? How do you decide which units join in the op fire? How do you decide if the machine gun crew just shoots alone to keep its op fire, or adds in other units for increased fire power?
I play solo a lot too and to start with the easiest question, namely the last one: in nearly all cases I forego including any other figures on the base with the MG figure in op fire attacks, unless the enemy has no more units left to move around, or in the rare instance that it's so incredibly important to take out a certain enemy unit or to stop it in its tracks, that I want to have the best odds possible and therefore include the two additional [regular] infantry. This is actually true for whether I play solo or against an opponent.
When do I activate op fire in a general sense? Well, the thing is, which is probably exactly what you're referring to, as I play both sides I KNOW what the activated unit intends to do (i.e. remain at normal range and fire or move into close range and then fire). I then just always "pretend" I don't know, and do what would seem to be the most logical moment to use op fire. An alternative may be to roll a die when playing solo in each possible hex you could do op fire in. On a 4+ you take the shot; on a lower roll you don't(or sth along those lines). If you still haven't taken the shot in the last hex the enemy unit could move into, you take the op fire shot automatically.
And the final question, how do I decide which units join in? Well, when I have multiple MG's I obviously have them all join in (as long as there's no range disadvantage then of course) as they can do so without becoming fatigued. For non-MG squads I don't really see much difference between solo play and "normal" play. You just include as many units in the op fire attack as you're willing to fatigue. For non-MG squads I actually rarely combine fire in op fire attacks, as this results in multiple units becoming fatigued.
Hope this helps.