I wouldn't have it be real-time for the security person. Let players setup these maps and if the guards or cameras see the infiltrator then he's caught and he loses, but the creator doesn't need to be playing at the same time. Just let people upload their configurations and other players can test their skills out against that security configuration for that map any time. The thing I like about this is that you can collect stats around a give players security setup and that way people can try out the hardest ones to see if they can get by. Maybe if you lose you have to wait 30 mins to try again or something. Then you can award the people with the best security setup or something like that.

For people who solve the setup, the creator can replay the mission in the eyes of the infiltrator to see what they did (or a god's view also). It would be fun to watch someone get passed your system I think.

Rather than having player2 lose when he's caught, why not include police and have player1 chase down player2 when he's been detected.

More great input - thank you so much.

Ok there's a few things worth noting. Players of stealth games, the good ones, they are patient.

You will need to consider if there's a time limit.

If not, I'm sure it could reach the point where the player with a clear advantage wins. I do have some suggestions for this, but maybe you'll already know what you want to do.

If there's a time limit, whichever player loses at time-end is at a distinct disadvantage.

With limited time, you know when you lost if there's a long distance to travel, for stealth player.

There's also a middle ground, conditions could extend the time limit. This may not be applicable.

What's important is you determine just how long every game's going to last. Once you know that much you might be able to figure out how powerful both players need to be.

A time limit would certainly add some tension since the infiltrator couldn't just take all the time in the world but would force him to advance. Extra time could maybe earned by completing voluntary bonus objectives like stealing important employee PDAs to introduce a risk/reward mechanic.

For some reason I'm thinking that getting immediately notified of a door opening is too much of an advantage, unless it's something that's reported by one of the guards or surveillance when they see it. Player 1 would have to consider if the time it takes to close a door is worth the risk to try decreasing his chances of being noticed.

I think it might be fun as player 2 to set up and changing patrol routes for guards. But knowing specifically what it is that Player 1 is targeting might make it too easy. But if there were say 10 different things player 2 is charged with protecting and player 1 is interested in only 1 of them, then player 2 has a reason to continually divert attention from each location.

It probably wouldn't take too much time to close a door, therefore I think it might end up being perceived as an unnecessary chore. Maybe not an instant notification, but only visual feedback instead? It would keep Player 2 busy having an eye on the whole map to watch out for clues like open doors, but zooming out too far should be disabled then. Guards alerting Player 2 when spotting something unusual is a great idea indeed.

Targeting one of out n possible objectives would be another great way to keep Player 2 on his toes. I would have to make sure that the infiltrator's target isn't too close to his entry point, remove choosing one altogether or automatically place the exit at the complete opposite end of the map, though, but that's no problem some good level design couldn't take care of. :)

What about this:

There is one "defending" player and there can be 3 - 7 infiltrators, and there are five control points on the map, if one infiltrator manages to reach 3 our of 5 control points he becomes the new defending player, the old defending player becomes an infiltrator, and all infiltrators are moved till they are a certain distance away from the nearest control point, all "control point reached"-stats are reset and any alerts are reset.

The defender needs to be capable of changing enough of the defenses to make sure the old defender has no usefull knowledge (at all)left of the defenses by the time he reaches the first control point(sooner would be better), the defender could for example send his guards in other directions to patrol.

A player could either score points through being in control for a long time, or by catching a lot of infiltrators.

It's a bit action-orientated, but it allows for a good flow of the game.
(and realy, nobody wants to be a defending player when the infiltrator goes afk, or decides to study that camera for five full minutes)

It would also need to be connected through a server, but that is pretty inherent on small multiplayer games, the game itself can be hosted on a player's computer
(You can consider letting whoever hosts the game be the defender)

I wouldn't have it be real-time for the security person. Let players setup these maps and if the guards or cameras see the infiltrator then he's caught and he loses, but the creator doesn't need to be playing at the same time. Just let people upload their configurations and other players can test their skills out against that security configuration for that map any time. The thing I like about this is that you can collect stats around a give players security setup and that way people can try out the hardest ones to see if they can get by. Maybe if you lose you have to wait 30 mins to try again or something. Then you can award the people with the best security setup or something like that.

For people who solve the setup, the creator can replay the mission in the eyes of the infiltrator to see what they did (or a god's view also). It would be fun to watch someone get passed your system I think.

I see the game needs more than just one single game mode.

Rather than having player2 lose when he's caught, why not include police and have player1 chase down player2 when he's been detected.

Being detected would not mean immediate defeat for the infiltrator, so chasing him down is meant to be part of the fun. Sorry for not being entirely clear about that.

I think about the metal gear solid mini-game where you had to stay out of the camera/soldier view cone and any detection the game was over and you'd start over. I loved that challenge!

Splinter Cell basically did this fairly well. If you can get 3 friends to play it is great fun!

What they did is:

- stealth team has more movement options than defenders (e.g. climb through ventilation system, defenders can only guard/mine the exits)

- stealth starting area is impossible to reach for defenders

- if you kill a stealth guy he respawns

- you play until the attacks reach their objective then you switch sides, faster team wins

- it can get tedious as defender if you have absolutely no clue, but it is usually fun

Things you can do if you have free time as defender:

- check through various vision options like motion detector, infra red detector or normal vision

- place traps like proxy mines in hidden spots to surprise attackers

- spread out and coordinate in your team to cover a large area

If you move the defense to an rts perspective there is also a lot of stuff to do, set guards, mines, detectors etc. Also if you add a timer so that the attacker doesn't stall it should be great fun.