Common children's game played on space habitats throughout the Civilized Galaxy. Zero tag is an adaptation of an ancient game with semi-mythical origins dating back to Old Earth. There are many versions of zero tag, but all are played in a microgravity environment. The preferred (by parents) field is a dedicated safe play area inside the hab, but children have been known to play in any space where their presence is not actively prevented. One player, designated as the chaser, must touch one of the other players. That player then becomes the new chaser. This continues until everyone tires of the game or until caregivers draw away too many players.
Children have invented thousands of ways to play zero tag; there are dozens of variants, each of which has over a hundred sub-variants. There are rules adaptations for playing in an enclosed space with or without maneuvering equipment (usually draglines and/or pneumatic or magnetohydrodynamic thrusters), and equally involved rules for playing in open space (which requires space suits and thrusters for most sophonts). There are many methods for determining which player first takes the role of chaser. Some players have adopted scoring systems — usually negative scoring where everyone starts with the same number of points and loses points each time e is tagged. The last player with points left wins. Still other versions are timed, while others are both timed and scored. Absolute zero tag is perhaps the most well known variant. Instead of becoming the chaser a tagged player must "freeze" instead — e is not allowed to freely maneuver until e is "thawed" by a tag from another player or, in some versions, until e drifts into a designated "heater" zone. Scored versions usually award bonus points for "thawing" other players.
There are also rules adaptations for playing aboard spacecraft. Many of the other rules variants involve handicapping in order to balance games between players with widely disparate capabilities. This is necessary when players can be of several unrelated clades.
Zeegrav-ball - Text by M. Alan Kazlev after the original by Kevin Self Popular sport among baseline and nearbaseline humans, especially those spending extended time in microgravity environments. Two teams of 12 players compete in a microgravity arena, paneled with springy, cushioned tiles. The object of the game is to place a small ball in a target as many times as possible within four periods of 15-minutes each. Galactic championships of the sport are broadcast via Known Net link to most connected worlds with large baseline-equivalent sapient populations.