In the most popular and well-written system using 2d6 for task resolution, Traveller, typically 8+ will achieve success. With no modifiers either way, that means a 15/36 = 42% chance of success. In Conflict, we have made it 10+, which is 6/36 = 17% chance of success. This is deliberate. We are not trying to reproduce Rambo, Jack Ryan, James Bond or Ethan Hunt, but the small unit actions of modern conflicts - teams of people who plan. We have allowed more bonuses to the throw, to encourage teamwork and planning. Part of this is assistance.
Someone else's familiarities may improve the odds; throw 10+ for the first person, 12+ for the second, and 14+ for the third; there may sometimes be limited to less than 3 assistants, but 3 is always the maximum useful.
If the throw succeeds then the primary may add +1 to their throw, at the first failure they must go ahead and use their expertise as it is, so for example a shooter may get their +3 for Firearms expertise to hit a distant target, but if they have a spotter assisting them, if the spotter throws 10+ then the shooter gets +4 instead. Each assisting familiarity or expertise brought in doubles the time taken to perform or prepare for the task whether it provides assistance or not.
A few examples will illustrate this. Most of the details would be invented by the referee during play to liven things up, but are not necessary. Nobody need study small unit tactics, radio protocol, marksmanship, traps or first aid to be able to play.
After they have casevaced Sgt Anna, Cpl Merkava, infantry, and Cpl Tony, medic, are ordered to scout forward in the direction of the sniper who'd shot Anna and who they'd called mortar fire on, to discover if he was struck, and if he was working alone. With the helicopter fading away into the distance, they move slowly between the wrecked buildings, among the destroyed cars, trucks and rubble. Trying to find a sniper's nest is normally an Observation/Tactical task, which Merkava is familiar with and thus gets DM+1; Tony is not familiar with it, but his general military experience means he is not completely incompetent and has DM+0.
Spotting a likely sniper's nest requires a throw of 10+, and Merkava has DM+1. Being in just a two-person patrol with not a lot of firepower, she wants to proceed cautiously, halving her speed but giving another +1. Cpl Tony keeps his eyes open, too, is also moving slowly giving him +1, and tries to assist, which slows them further, so that overall they're moving at one-quarter normal speed.
Tony's player throws 4,5 for +9, but because he's moving slowly this becomes +10 and he is able to say, "I'm pretty sure it came from that building," pointing to a severely-damaged three story office building. Now Merkava has +3 in all - one for each of her Obs/Tac familiarity, moving slowly and Tony's assistance. Her player throws 4,3 which with the DM+3 makes +10. She crouches down behind a wrecked car and looks through her sights, "I would have set up right there," she says, then lowers her rifle and points to the blown-out corner window on the third floor, "it has a good view of half the area, he could have fired from there. Let's head in. But first - gear check."
They go over their gear to see how many reloads they have, their torches working, and so on. "Let's hear you," says Merkava, and gets Tony to jump up and down a bit to see if he has any loose bits of kit which might fall off or make too much noise. This is a Stealth check; neither has familiarity with Stealth, only their basic training giving them DM+0. However they have considered the issue and so the referee rules that their next Stealth check will be granted a DM+1 as a result.
Tony points his weapon, watching, while Merkava dashes across the street and takes position by the side of the entrance. She then holds her weapon ready to fire either at anyone coming out of the doorway, or anyone appearing behind Tony as he runs across the street to the other side of the doorway. He arrives unmolested, and she pulls her cam kit out of her pocket, which has camouflage cream and a small mirror, and holds the mirror around the corner. She looks, puts it back in her pocket, and looks over at Tony, her fingers mimicking walking up stairs. He nods, and she goes in.
Inside is a wrecked lobby with rubble all round, but some surprisingly intact stairs. They take their time, feeling for solid boards, and trying not to step on the bits of broken glass, which grants any Stealth attempt DM+1 on top of the +1 they already had. With Merkava ahead and Tony behind, they go on up the stairs. The first floor above ground has been largely cleared of debris and obviously has no-one in it, and as they turn the flight of stairs to go to the second floor above ground, the referee calls for a Traps check. Neither has the expertise or any relevant familiarity, but they are moving slowly, and Tony is backing Merkava up with watching.
Tony's assistance throw is made first, and he throws 5,6 for +12 with his DM+1 going slowly. Merkava as the primary throws 4,4 for +8, with +1 for going slowly and +1 for Tony's assistance, she just spots it - as she moves forward, Tony puts his hand on her shoulder and points down with his rifle - there is a wire across the floor at ankle level attached to some empty ration pack cans, an alarm trap. She nods, he lets her go, and they step over the wire as they move further up the stairs.
Now at the top of the stairwell on the third level, they see a lot of debris which has been shaped into makeshift walls. The referee does not require they throw to see two men in the far corner, exactly where Merkava had thought they'd be, lying exposed to the sunshine as a mortar strike had taken away part of the ceiling. One man lying a few metres from the corner no longer has a right arm, has one leg twisted under him unnaturally like a child's tortured Barbie doll, and has a large chunk of his upper trunk missing, with burned organs exposed - blown apart by a mortar bomb. There is no sign of his weapon, if any, or scope. The other is lying under a metal girder and some broken bricks which had fallen with the strike, his eyes wide, his rifle near him. As they watch, they hear a brief gasp and then a moan, another brief gasp.
No throw is required for Tony to say, "He's alive!" and his medic instincts kick in and he rushes forward. "Wait you stupid bastard!" cries Merkava. Fortunately the enemy were not suicidal maniacs and so have not booby-trapped every square metre around them. Tony kneels down by the pinned sniper and begins looking him over. He is only semi-conscious, and blood oozes from one ear. The girder looks heavy, and blood is oozing from his chest around it. He gasps rapidly and moans.
Merkava comes over and sees the sniper's rifle nearby, removes the magazine, pulls open the bolt to eject the round in it, and lays them at a distance from the enemy. While Tony gets into his medical bag, she checks what she can reach of the enemy and finds he has a backup handgun on his hip. She treats it as she did the rifle. She then steps back and crouches down on one knee, keeping an ear out for anyone following them up the stairs, occasionally glancing about.
The referee informs the players that the enemy sniper has in game terms:
- head, INC, blunt - ie concussion
- trunk, KIA - probably had decayed from INC due to his being left there for an hour or so before they found him
- WIA, left arm
- WIA, right arm
- a heavy girder on him which will have to be removed before they can treat his head or trunk.
- which means throwing 10+ for Strength/Lifting and Physician/First Aid, if they want to help him