Okay, we'll be returning to our game after Christmas is over and I have something rather cool planned. I'll actually admit that it's not all that logical from a business point of view but I'm ignoring that because it'll hopefully be a lot of fun for the players.

Now a part of this is going to be someone close to the group being replaced by an infiltrator who's then going to lead them into a trap. Now I want to be fair and give the players a chance to spot this (I'm fairly sure that if they do then they'll follow my trail of breadcrumbs anyway so they can get to the bottom of the whole thing), but I don't want to have it screaming out at them.

So...

Can anyone suggest some subtle clues I could drop to twig the players in that something is wrong and get them to roll to work out what?

The person doesn’t order their favorite food when it’s the special that day.
Holds their left hand over their right when normally they hold it right over left. (stole this from GI Joe 2)
Use of a non local turn of phrase (skillet not pan, elevator not lift, coke not pop)
Left handed instead of right handed
Doesn't have that ache (or complain about it) in his knee when it rains



hope this helps

Easiest & fastest way is for the infiltrator to miss out on an inside joke of the group, especially if it was one started by the PC he is impersonating. That is a good RP way of bringing it up IMO.

It depends a lot on how the group interacts.

Draw too much attention or request perception rolls and the players will tweak to something being up.

Missing an inside joke or the missing ache/complaints as suggested above are good ideas but again depends on the players.

Contacts may also tweak to something amiss, which in turn may require the infiltrator to silence them, potentially leaving clues.

In my experience with double crosses, players either completely miss the mark and don't pick up any clues (even going so far as to conclude that they weren't double crossed and that someone had taken out the Johnson that didn't pay them for the job) or they are so paranoid they think everyone is trying to double cross them and they take out three or four people who were on their side. Sometimes both. And that's regardless of what hints and how many I give them. Especially, once they've decided on some truly ridiculous theory that they'll cling too regardless. So maybe don't stress about it. You're just herding cats anyway.

Though if you're serious about giving it a go, from most subtle to least:

If you get in character for NPC's change the character slightly.
Have him start the conversation by saying that he's: Drunk, high, sick, hasn't slept in the past 48 hours, or otherwise give some heavy handed excuse for why he might be acting unusually.
Tell the team that they're going to need to go through a high security zone and so shouldn't take any weapons (while leading them to the trap).
Have his comm in a different mode than usual.
He's got a black eye or otherwise is somewhat mangled to hide any differences in appearance.
The path takes them through an area where the teams sniper can't provide cover.
(assuming the double has access to previous communications) Give the team something that he previously promised them and already delivered.
He tries to convince them to compromise their security (like make their comm's public) or so something that's obviously a bad idea (take a hit of novacoke before they leave for the trap).
He contacts them from a different number than usual.

ask a team member to do something/use some skill that the real person who's been replaced actually does better. they can cover with 'I thought you'd like the practice'

That's really clever. Depending on the prep time they had for this transition it could make a very good reveal.

As for my own suggestion, if it's one of the absent PC's then give the infiltrator an addiction flaw. Your players will either click that something isn't right and confront the character or they will think your being THAT GM and punishing the absent player's character. Either way it should be amusing when the reveal comes around!

In the end I went with 'different comm number' and 'reused disguise' for my mole.

The hints that my players were in VR were, in order until they worked out what was happening:
1) Employer appeared out of nowhere in a secured building.
2) Employer offers ten time more cash than the job would normally net them.
3) Walker suggested a plan that would involve mass civilian casualties.
4) Enemies spawned from locations they shouldn't have been able to be hiding.
5) Enemies have bottomless magazines for their assault rifles (considering they were using massed suppression fire this was bad).
6) Spirit summoning felt wrong to the shaman.
7) Astral was wrong. all of the astral, all of the wrong. (at this point they were figuring they were fighting magical illusions or something like that).
Entire group was dumpshocked as power to their VR units was cut. (They worked it out at this point...)