Some good team-building games include Legoman and Mine Field. Both of these games take less than an hour to play and are perfect for groups of all sizes and ages.
Legoman is a problem-solving game. The game requires a set of Legos and for the participants to break up into teams of three to six. To start the game, the instructor puts together a sculpture using the Lego blocks. Then, it's up to the teams to recreate that structure to the best of their abilities. The structure is put in an area an equal distance away from both teams. One member from each team is allowed to view the structure up close. Using only their memory and words, they have to come back and tell their teammates what the structure looks like. The game continues until one of the teams successfully recreates the structure.
Mine Field is a team-building game that improves trust. The game requires an empty room and objects to represent the mines. The instructor places the mines randomly in the empty room. A member from the team is blind-folded and has to make it to the other end of the room without hitting a mine. The other teammates guide the blind-folded member using only their words.