Second Edition Warhammer 40,000, released in 1993, featured the Tyranids in the supplemental books Wargear and Codex Imperialis, and then later in their own devoted army Codex. An extensive model range was released, representing most of the units described in these publications. The army was, however, very different from the factions previously seen in the game.
The Tyranid player now had access to a range of unit types roughly equivalent to that of the other factions, including the Hive Tyrant, Termagants, Hormagaunts, the main adversary in Space Hulk Genestealers, Gargoyles previously seen in Epic 40,000, Tyranid Warriors, the Carnifex, Zoanthropes (a Tyranid psyker in addition to the Hive Tyrant), Lictors, and the Biovore.
The Tyranid supplement to Third Edition Warhammer 40,000, like most of the other supplements released at that time, focused on revamping the rules for the various units while maintaining the overall structure of the army, so that veteran players would not find their older collections unusable or less useful in the new edition. It did however add some new units and tweak the behavior of others. A brand new model range, somewhat different from the older ones, was released to coincide with the new publication. New units included: the Tyrant Guard and Raveners.
The Third Edition Codex, as with a number of subsequent publications, included an army list which allowed far greater flexibility to the player than previous army lists, allowing extensive customization of units; at the time more so than any other available faction. Unit types noted as a 'Mutable Genus' in the main army list were permitted to be extensively modified by choosing from numerous options in the 'Custom Hive Fleet' section of the book. The options available bore a resemblance to the random equipment tables featured in Rogue Trader, but were no longer randomized.
The nature of the army list in Third Edition further cemented the Tyranid army's reputation for fielding vast numbers of models, allowing the player to overwhelm an opponent with weight of numbers. This was even more pronounced in the variant Seeding Swarm army list published in White Dwarf and later in Chapter Approved, which represented the initial stages of a massive Tyranid assault and even further emphasized the use of many expendable, 'cannon-fodder' type units. One of the more overlooked abilities is the new "without numbers" rule, which allowed for literally an unlimited number of gaunts in a single game, emphasizing the "cannon-fodder" trait of the Tyranids.
The release of the fourth edition codex added a new model range, new rules, and new units, most notably the Broodlord, and revamped units such as the Carnifex. This new codex also enables Tyranid players to field a grand total of eight large Tyranids to be fielded in a 1500 point battle, although the player would still have to field compulsory troops choices. With this concept Tyranid armies can now boast either the many troops and/or a just few powerful units.
A new Tyranid codex was released on January 16, 2010, written by Robin Cruddace. It included 15 new species of Tyranid, and legendary heroes like the Swarmlord, Old One Eye and the Doom of Malan'tai. In addition, some models saw a point cost reduction, which allowed certain Tyranid armies to field more units, though, notably, this was not the case for all Tyranid units, as several saw point increases in this edition.