The following is a list of common and perhaps not-as-common suggestions for various water war games to help keep things cool when its hot.

FREE-FOR-ALL
Number of People: Any (at least 3)
Duration: Any length of time available. Can be made short or long depending on interest.
Area Required: Any location which can afford to get wet

Overview
One of the most common forms of water war. Basically, it is an every-man-for-themself game in which each player attempts to soak everyone else while trying to remain dry. There is no way to score or determine who is winning. One just knows how one is doing simply by how wet and uncomfortable one is at the end of it.

FREE-FOR-ALL - ONE HIT KILLS
Number of People: Any (at least 3)
Duration: Any length of time available. Typically a shorter game.
Area Required: Any location which can afford to get wet. However, can be made more interesting if done in an area with a lot of hiding places.

Overview
Another common form of water war. Basically, it is also an every-man-for-themself game in which each player attempts to spray everyone else with while trying to remain dry. Anyone who is hit by a blast of water, no matter how small, is out of the game. Out-players are forbidden from continuing to hunt others down and must wait for all but one to be sprayed. The one who manages to remain unsprayed is called the winner. Though not that realistic in a real warfare sense, it does allow for a little more stealth and strategy to be used. Since one hit kills, these games tend to be relatively quick. A waiting area should be set for the players who are out to go to while the others complete the game.

TEAM WARFARE
Number of People: Any (at least 4; at least 2 per team)
Duration: Any length of time available. Typically long but can be made short if need be
Area Required: Any location which can afford to get wet

Overview
One of the most common forms of group water war. Basically, the group of people are divided into two or more opposing teams. Each team attempts to soak the members of the other team while trying to remain dry. There is no way to score or determine who is winning. One just knows how one is doing simply by how wet and uncomfortable one is at the end of it. The nice thing about team wars is that one can practice using various formations to attack or defend against the opposition. Also, it is always nice to share in a combined soak.

Good team-war games allows one to make the most of one's knowledge of strategies, setting traps, ambushing, etc.

TEAM WARFARE - ONE HIT KILLS
Number of People: Any (at least 4; at least 2 per team)
Duration: Any length of time available. Typically shorter than a team warfare game but can be long at times
Area Required: Any location which can afford to get wet

Overview
Another common form of group water war. Basically, the group of people are divided into two or more opposing teams. Each team attempts to soak the other team's members while trying to remain dry. When a team member is hit, they are no longer allowed to attack and must go to a waiting area or sit on the ground (whatever rule was agreed upon prior to starting the game). Once all members of a particular team are eliminated in this fashion, the remaining team is declared winner.

Good team-war games allows one to make the most of one's knowledge of strategies, setting traps, ambushing, etc. The "one hit kills" rule just makes this type of game go much quicker as well as making every shot count. The only drawback is that the power of one's water weapons no longer matters as much since one hit from an XP 20 can kill though that hit would not have really soaked the target.