Hot Box (or simply Box) is a non-contact team sport which is similar to Ultimate, but played on a smaller field and with fewer players. Like Ultimate, the object of the game is to score points by passing the disc into the endzone; however, in Hot Box there is generally only one end zone and it is of much smaller size than an Ultimate end zone. In this way, Hot Box is a "half-court" (see basketball) variant of Ultimate. Because of these reduced requirements, it is often played when not enough players are available to play Ultimate.
For the most part, Hot Box follows the rules of play of Ultimate. The major differences are:
- Team size: Box is usually played with two teams of three or four players. If ten or more players are available, most people prefer to play Ultimate rather than Box.
- Field of play: Box is played on a square field of approximately 40 yards on a side. A single square end zone, approximately five feet on a side, forms the center of the field. Each square is marked with four cones on the corners.
- Turnovers: There is no out-of-bounds in Box. If the disc is turned over (dropped, intercepted, etc.) inside the outer square, the team which is now on offense must clear the disc by completing a pass outside the outer box before they may score a goal.
- Goals: When a goal is scored, the scoring team retains possession. They must clear the disc before they may score again. It is customary for there to be a stoppage of play when a goal is scored, but in some circles the scoring team may immediately continue play.
- No Fouls: Unlike Ultimate, Box is usually played more like pickup basketball, with some amount of physical contact allowed in and around the box area. Normal fouls & violations in Ultimate (picks, strips, travel, contact) are typically not called. Some games of box also allow for intentional strips, and hard (though still usually friendly) contact.
Many variations on the rules of Hot Box exist. Common variants include changing the dimensions of the field, using a circle instead of a square for the clear line, a stall count of 5 or 7 (instead of 10), and a "no poaching" clause which prevents defenders from guarding the endzone instead of their assigned player.
Some variant games also exist. Double Box involves a short rectangular field with two small end zones rather than one; there is no clearing line, but when a team gains possession of the disc after a turnover they must attack the end zone that their opponents were not. Invalidimate was developed in the UK as a way to include injured players in practice; the "invalid" stands in the goal and is the target receiver for both teams. Two invalids can also be used in Double Box, with the additional rule that every player on a team must touch the disc (including the defensive invalid) before the offensive invalid can catch a scoring throw.