On any given day we can have any number of players, up to ten, so that's not a limitation. Keep in mind that setup, play and packing up needs to be done in the hour. My coworkers are all experienced board gamers, so complexity is not an issue.
This is another card game that's really simple to set up. I find that I play better when I'm not fully paying attention - always a consideration when food is involved. It theoretically supports as many people as you want (the wiki page says 2-6, but I've played many games with more). You should be able to complete somewhere between 0 and 12 games in a one-hour lunch.
So where i work we are between 5 and 8 depending on the days to play every lunchtime for around 1h. For now my impression are (Roughly sorted from best to worse but including only the good ones) :
It's one of the first game we played and still a hit in our group. There is a good level of strategy, medium amount of chance and great level of interaction between players.
One of the problem we had was the total time of the game that could vary a lot if you have players taking a long time to choose a character (There is a lot of strategy in this choice as if you are too greedy and so predictible you will either end dead or without any gold). We solved it by imposing a fixed 45s time to select a character.
The game need at least 5 players to begin being really fun.
Always a big hit, it's easy to play, need nearly nothing (The cards could be contained in a pocket) each round is fast and being dead is as fun as being alive as you could see how good liars the others are... There is a big amount of strategy, small amound of randomness and very hight amount of interaction between players.
The only problem of this game is that the number of players required for it to be fun is 8 and it require a non playing game master so our group is not often big enough to play it.
We play it nearly every day after another game when we have time. It's a pure bluff, small amount of randomness, small amount of strategy, good amount of player interaction game.
It could be played in 10-15min without problems even with 7 players (Even if the box say 6 max)
The rule that there is one losser and all the others win make it really interesting as every one try to attack the player that is losing, making him lose more xD
One of the game we play the most even with it's problems as all players in our group like it and it became the default solution when game choice is too complex (due to one or two players refusing to play some other games this day)
The game is fun with lot of interaction between players, lot of randomness, and a moderate amount of strategy.
The big problem of bang is it's randomness making some games very fast (Sherif with 4 life points near billy the kid with 4 bangs in hand being against him) and others very long. Also one player could die really fast and watch the other continue to play for a long time, witch is not fun at all.
Regarding the time to play on lunchtime you absolutely must get one of the extensions adding the one special rule per turn cards (Fistfull of cards or High Noon). As the number of extension cards is selected at start and the last one is fatal really fast for everyone it put an upper value to the number of turns possible. 8 cards for a 45min game with 6 players is a good bet for example. (6 players being one of the configuration that work the best)
The link to boardgamegeek.com on the title point to the bullet that contain everything you may need.
We currently played with only one green card authorized as otherwise it allow someone to protect himself too much and remove claus the saint from the game as it take too much time to play.
Except for one of our player that doesn't have any immagination this game is really great and a lot of fun especially if you know the players you play with as you will tailor what you say for some of them to get the hint and others to miss it. Sometimes it work and sometimes you discover that everyone read the news yesterday and go your hint or that they all know the nearly unknow actor that you named...
The game is fast enough to play on lunchtime (The number of points or number of turns to win could be chosen depending on available play time), the maximum number of players is 6 (Playing with 3 or 4 players could be done but it is really less interesting, it should be limited to 5 or 6 players).
There is a small amount of randomness, moderate amount of reflection and no direct interaction between players outside of the narator/non-narator separation.
The box is uselessly big but could be discarded as a simple paper or a white-board is better to count points anyway.
Fun, easy to play, pretty fast (as the array of cards is fixed, the time don't really depends on the number of player and stay around 20 minutes) playeable up to 10 players. It's a great game for lunchtime.
The game have a high amount of randomness and player interaction and small amount of strategy for miners / great amount of strategy for saboteurs.
We always play without a random amount of saboteurs as getting only one nearly assure that he will lose.
If the number of player is limited to 4 or 5 it could be played in 1h (more and it's too long) and the game is really fun with lot of interaction between players (Playing a +10 levels to a monster the other player used all it's bonus to be able to kill is allways so much fun) a good amount of randomness and a little bit of strategy.
Some of our players don't like this game as the rules are not really well defined sometimes and lot of cards change them. It's also the only game where some editions explain that cheating is authorized (There is a rule for what happens to you if someone notice) and that if there is a debate the player owning the box decide the outcome :D
The game is simple but there is finally a good amount of strategy as well as randomness and there are a moderate amount of player interactions. It's pretty fast so it could be played multiple times in one hour. The game is great at 4 players.
Good game of bluff and guess-who-i-am with a small amount of randomness, big amount of strategy and moderate amount of interaction between players. It could be played up to 8 players according to the box but more is ok. The rounds are very fast to play and you could do as many as you want.
Games for two players follow we don't play them as often so i separate them. It's good to have them to be able to split the group.
Basically an alternative to magic. Very strategic and interesting but should be limited to 2 players for lunchtime games as more players is too long, getting well over 1h.
Really great nearly pure reflection game for two players. The game is small to transport and could be played in 30min without problem (The time depends a lot on the reflection time of each player, as with chess a time limit for reflection is sometime usefull)
Magic: The Gathering
My co-workers and I regularly play Magic over our lunch break. Setup time is minimal, and the game scales well from 2-6 players.
With 4-6 players, we often have time for two games; with 2-3 players, three or four games.
Having 10 people play at once might make the game run too long, though. In that case, I'd recommend splitting everyone up into two groups of 5.
Race For The Galaxy
This is the default game for our group when under time constraints. It's very complex for it's play time (20-45) minutes, often making you feel like you've played a game twice its actual length. As such, it's also very rewarding. Plus, there are multiple expansions if you wish to explore the game further, and they still keep the play time to under an hour. The expansions also let the expand the number of players from 4 to eventually 6. Because of the simultaneous turn mechanic, the game time is not usually lengthened by adding more players. Just be warned that the first (learning) game will take much longer. Our first game almost 2 hours, the very next game was 20 minutes.
Though there's a bit of setup it's still reasonably quick, and you get a lot of meaty gameplay in 30-45 minutes. It's designed for 3-7 players and has a very solid 2-player variant included (2-player takes longer than 3-7, be forewarned).
It's dead simple to set up and easy to learn. I worked in a office where we regularly had two games going every day. Anyone was welcome to play, just sit down and deal. We usually could play two full games (to 10 points) in a one-hour lunch break.
As a bonus (having just now skimmed the wikipedia page), there are apparently variations for 6 or 8 players if you need to support more people.
It's for two players only, but most games only take 30 mins or so and the rules can easily be picked up in 5 minutes.
It might be too simple for an experienced group, but Apples to Apples is great for lunch breaks, particularly as you can add / remove people as needed.
It's dead simple, so it's easy to get new people involved, and the only real requirement is to have ~4 people. I've played it with groups as large as 9 before ... 10 shouldn't be a problem.
The only problem I've run into with the games is that at my current place of work, there's a fair number of people who didn't grow up in the U.S. and aren't native english speakers, so some of the cultural references (mostly people) are difficult for them.
I got beaten to recommending 7 Wonders, which certainly fits your needs (7 players, ~40 minutes), so consider this a +1.
If you like Dominion, consider AEG's Thunderstone. Deck-building, with a dungeon-delving theme.
Steve Jackson Games' Zombie Dice and Cthulhu Dice are decent for large groups. Of the two, I prefer Zombie Dice, as it has a bit more decision-making and agency.
...while we're on dice games, there's Roll Through The Ages It's only up to 4 players, but it plays in an hour or less and conveys an enjoyable civ-building experience.
If you're okay with print-and play games, I made two that might fit the bill: Office Gossip ( http://www.invisible-city.com/play/435/office-politics ) is a Werewolf-style game that doesn't need a player to sit out and be the narrator – everyone gets to play. Uncontrolled Squid ( http://www.invisible-city.com/play/211/uncontrolled-squid ) is a team-based contested bidding game – all you need are standard Poker decks (1 per four players).
Edit: One more suggestion – Prolix from Z-Man Games is a word game for 1 to 5 players that plays quickly, is very portable, and is quite fun. The premise: Think of a word that uses as many of the (ten?) letters on the scoring board.
Just played for the first time last week. If you have experienced board gamers, it probably wouldn't be something you play every day, but a game only takes about 15 minutes, and as soon as it's over, players are usually eager to play another.
It's an auction game that is themed on buying and selling real estate. Players start with money that's used to bid on houses of varying values (with art ranging from doghouses to mansions). After the houses have been purchased, players then enter a second round of bidding for more money, and bid with their purchased houses from the first round.
We had mix of experienced gamers and newbies, and it was just as well received by both. 3-6 players.
Blokus is an outstanding game that's also very easy to track down, as it's available in most big-box stores. Each player gets an assortment of Tetris-like pieces in a single color, and must place one per turn if they can. Each piece placed must touch at least one piece of that color - but only at the corners. That's pretty much it for the rules, but this is a tense experience with quite a bit of depth and no randomness.
The biggest downside is that it's very clearly designed to be a 4 player game (though I'm told that there are a couple of 2-player variants that are worthwhile). I haven't played it, but I've been told that Blokus Trigon works well for 3 players.
How about Are You the Traitor? No setup to speak of, socially dynamic, and the play is rapid paced and doesn't require careful tracking of past events/actions/state (a plus when people are distracted by food).
For two players, we have played Dominion - with and without an expansion. We have also played some of the Gipf project games, although they are only two player and both people will need to stay focused to finish the game. Short setup time and quick teardown mean most of the time can be spent playing.
Other options are more "traditional" games - I saw Euchre recommended. Shanghai/Hollywood rummy (or any of the rummies) can be played usually in under an hour, and because they have "hands", you can play over a few days if necessary. Also, since it is just shuffling to setup, it is a quick setup. :)
Treehouse - quick, pretty much as many players as you want, setup is easy, take down is easy. Not presently available from the manufacturer (Looney Labs) because they are changing their packaging, but you can probably still find sets in local game stores, or wait a bit for their new packaging.
Launch pad is a simple quick strategy game that involves building rockets, and preventing others from building them. It's a lot of fun.
As for a game that would involve so many people, well, Bang is probably your best bet, and that's a really quick game. It works best with a lot of people, although it does have the disadvantage of having some people sit around with nothing to do for some time, as there are players eliminated early on in the game.
Starfire, played as a tactical game, is fast and pretty good for multiple players. Some prep needs be done outside play, namely ship sheets, but with experienced players, a fleet battle can be played in under an hour with a dozen ships on a side or more.
I've played a roughly 30-ship per side battle in 35 minutes before, tho' both I and the other player had counters bagged before hand, and fleets done up and printed out before hand.
Man To Man and The Fantasy Trip's Melee and Wizard
The GURPS combat system was released as a board game, entitled Man to Man. It's pretty fast playing, and very tactical.
Likewise, SJ's prior RPG, the Fantasy Trip, was released as two board games and a roleplaying expansion. The board games, entitled Melee and Wizard, sold quite well. Both are extremely tactical, and some copies keep surfacing in new or like new condition regularly. A later revision, Dragons of Underearth, was a board game with full RPG-style character generation, but limited skill and spell selections.
It's very possible with either to play out a multiplayer game in 30-45 minutes.
With 1 ship per player, Full Thrust plays VERY quickly. It's a miniatures game of space combat. The Babylon 5 version used 12-sided counters; there is no reason one can't make similar ones for the canon FT races. I've played multi-sided battles with novice players in 30-45 minutes, to conclusion.
Note that the rules are available in PDF for free from the GZG website; the link is to the downloads page.
If you can find the Chameleon Eclectic Babylon Project EarthForce Source Book, it includes a Babylon-5 themed version of the rules.
If you've ever got just one other player or split into a group of 2, Memoir '44 is a great game. It's a WWII-themed game that's scenario-based, with 16 coming in the box and more available on the publisher's website (you can also create your own, if you're feeling ambitious). Not all of the scenarios are balanced between the Axis and the Allies, but the publisher's site has win/loss percentages for each scenario based on logged plays, so I've been using that data as a handicap to balance the matches when my experience doesn't match my opponents.
Setup looks intimidating, but I played my first game, including setup and rules explanation, in about 45 minutes. There are also rules to play on two teams with up to 8 people if you've got expansions and/or two copies of the base game; I haven't tried this, but I've read that it takes more than an hour, so that might not work for a lunch thing.
Coloretto is probably the best short game I've ever played - most games should take no more than 15 minutes to play. It's a card game in which you're trying to collect cards in different color groups. The more cards you have in any given color, the more points that group is worth at the end of the game - but only 3 colors (chosen at the end) count as positive points, and any other groups count as negative points. It's very simple to play and is the only game I've played I'd recommend without hesitation to anyone who has never played a "hobby" board game before.
The same designer later released Zooloretto, which is a board game adaptation that adds a little bit of complexity and playing time (though still straightforward and would still be appropriate for lunchtime board games) that I think is equally good. I'd probably always recommend Coloretto first, since it's cheaper, faster to play and more portable, but if you like Coloretto and/or want something with a little bit more depth to it, Zooloretto is also worth checking out.