Mini-campaign system where the results affect the next game sound interesting – the LDRG should try to keep their own casualties low (small patrols cannot afford many), and try to avoid rising any early alarms from the opposition. For example, an airfield raid mini campaign of three parts could start with the LRDG trying to sneak past enemy patrols in their approach to the airfield, second part could then involve a surprise assault on the airfield with guns blazing, and the third part would see a daring escape by the survivors back to their own lines.
I tried to think of how the sneaking past the enemy patrols could be translated into a tabletop scenario, and came up with the following (borrowing a few ideas from some sneaky SF scenarios I have read lately). Not able to try it out myself at the moment, so not sure how well it would work in the practice, but feel free to borrow the concept in any form you want (it could perhaps be also converted to other settings, including post-apocalyptic SF).
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PATROLS IN THE DESERT
Setting: somewhere in North Africa around 1941.
Forces: LRDG patrol of three vehicles, and six enemy (Italian/German) patrols of one vehicle each. Use whatever unarmoured vehicles you deem appropriate for both sides (though if the LRDG vehicles mount an anti-tank gun, it might be possible to substitute 2-3 enemy patrols with a single armoured car, starting in reserve).
Terrain: a section of desert with plenty of terrain for cover, such as sand dynes or dry wadis. It can further be assumed that the weather limits visibility over long distances, e.g. due to heat haze or wind gusts pulling up dust clouds from the desert floor.
Deployment: LRDG patrol is placed in the middle of one table edge. Three enemy patrols are placed in different locations around the table, sufficiently far from the LRDG patrol (with no line-of sight) and headed to a random direction (not directly towards LRDG patrol). Remaining enemy patrols are placed into reserves.
Objectives: LRDG patrol has to get as many of their vehicles as possible off the opposite table edge, preferably without the enemy rising an alarm. Enemy patrols task is to intercept the LRDG and/or alert their own base about the intruders, but first they need to spot the LRDG patrol.
Special rules: no special rules apply to the LRDG patrol, while the following rules apply to the enemy patrols.
1.) Reserves: roll D6 at the beginning of each turn for each patrol in the reserves, on a roll of 6 it enters the table from a random point on one of the side table edges (the ones that LRDG does not enter/exit from), pointing in random direction (not off-table). Any patrols that exit the table through random movement enter the reserves, while any patrols deliberately exiting the table are permanently removed from play.
2.) Initial movement: until the first enemy patrol has spotted LRDG patrol (by drawing LoS between two vehicles at any time during either players movement), the direction and speed for each enemy patrol's movement is determined in the following fashion.
To determine direction, roll D6:
1-3: vehicle maintains current direction
4-5: vehicle changes direction (roll randomly for new direction)
6: controlling player can change the direction (pick new direction before rolling for speed)
Speed is determined my dividing the maximum speed of the vehicle by 6, and then multiplying this number by D6 (ie. on the roll of 1 the vehicle moves at 1/6 maximum speed, on the roll of 6 it moves at maximum speed and so on). If a patrol spots LRDG during this movement, they still have to complete the full movement (from the next turn onwards they will be able to move as desired by the controlling player).
3.) Movement after first contact: once the first enemy patrol has spotted the LRDG patrol (and guns have started blazing), the other enemy patrols will change their behaviour, but will not come under full player control until they have themselves spotted an LRDG vehicle.
In case enemy patrol (that has not yet spotted LRDG vehicle) can draw LoS to another patrol that has spotted an LRDG patrol, they will move towards that vehicle at full speed to find out what is going on (in case they can observe multiple such vehicles, determine randomly which one they will head towards). Otherwise, roll D6 to determine their actions:
1: vehicle maintains current direction, moving at full speed
2-3: vehicle turns to random direction, moving at full speed
4-6: vehicle turns to a direction picked by the controlling player, moving straight at full speed
4.) Random movement and terrain: in case random movement brings a patrol in contact with impassable or hazardous terrain, it will stop just before making contact. In the next movement phase, treat any result of "vehicle maintains current direction" as turn to a random direction instead.
5.) Alerting base by radio: enemy patrol that has spotted LRDG vehicle can try to alert base by radio, though not on the same turn as it spots the vehicle. Furthermore, it cannot shoot in the same turn as it tries to sent the alert. To determine if the attempt was succesful, roll D6: on a roll of 6, the base has been alerted (after this, further attempts to alert the base have no effect), and also any vehicles remaining in reserve become aware of the on-going conflict and will arrive table on future turns on roll of 4+ (instead of only 6 as on earlier turns). Enemy patrols that have exited the table cannot try to send alerts, though patrols on table can attempt to alert the base even after all LRDG vehicles have exited the table (at this point success will be automatic).
Aftermath: any LRDG vehicle that exits the table via the opposing edge will be available for the next game. If the enemy patrols have managed to rise alert by radio, the defenders in next game will be alert, otherwise they will be taken by surprise.
Designer notes: if the LRDG player gets lucky, he may be able to sneak off the opposite table edge without getting spotted. In case his vehicles get spotted, he can either try to hit the pedal and run for his objective, or try to attack the spotting enemy patrol before it can send a radio alert. In the reverse, player in control of the enemy patrol has the choice of either running away from the LRDG patrol (in order to rise an alert) or to attack them in an effort to intercept them or cause casualties. The enemy patrols intentionally suffer from "stupid sentries" effects that limit their movement until they have spotted LRDG vehicle themselves.