Card Games
When you take your lunch break along with colleagues, card games are a way of relaxing, but also socializing away from the stressful working environment. Since lunch breaks are short, do not choose overly tactical games and go for more fast-paced options. A game of Uno, for example, is an easy-to-learn game with rounds rarely going beyond the 10-minute mark, giving you the opportunity for a rematch after a lost round. When you only have a standard 52-card deck, Crazy Eights and Kings Corners are easy options; you can learn about each card game's rules at Pagat.com.
Back to Childhood
Quick games requiring no additional equipment other that your bare hands, such as thumb war and rock-paper-scissors, may be the only option for play during very short lunch breaks. If you end up with less than 10 minutes after finishing your lunch, ask your colleagues to play some quick rounds. Another advantage of these simple games is that even if your colleagues are not aware of the games' rules, it is easy to learn them on the spot.
Flash Games
When you are alone during the lunch break, you can use your smartphone, laptop or even your work computer (if you have permission), to spend some time on simple Flash games. Such games are available online at numerous websites, including Miniclip and Addicting Games. Contrary to commercially available games for games consoles, these titles focus on simple tasks and allow you to progress fairly quickly, making them ideal during a quick break.
Board Games
Like card games, board games can bring colleagues closer and guarantee a few fun moments during lunch breaks, provided you keep it short. Battle Line, Yinch, and Ingenious are board games you can play in under 30 minutes. For more games search at BoardGameGeek using the tagline "quick." In addition, suitable games for such occasions are shortened versions of traditional games, such as Scrabble and even chess. In theory, you can set a strict time limit for all board games to step up the pace, so that you can fit them within the time boundaries of your break.