Chrono Trigger features standard role-playing video game gameplay. The player controls the protagonist and his companions in the game's two-dimensional fictional world, consisting of various forests, cities, and dungeons. Navigation occurs via an overworld map, depicting the landscape from a scaled-down overhead view. Areas such as forests, cities, and similar places are depicted as more realistic scaled-down maps, in which players can converse with locals to procure items and services, solve puzzles and challenges, or encounter enemies. Chrono Trigger's gameplay deviates from that of traditional Japanese RPGs in that, rather than appearing in random encounters, many enemies are openly visible on field maps or lie in wait to ambush the party. Contact with enemies on a field map initiates a battle that occurs directly on the map rather than on a separate battle screen.
Unlike most other role-playing games at the time, combat in Chrono Trigger
occurs in the same area where general navigation occurs, with all enemies visible on screen.
Players and enemies may use physical or magical attacks to wound targets during battle, and players may use items to heal or protect themselves. Each character and enemy has a certain number of hit points; successful attacks reduce that character's hit points, which can be restored with potions and spells. When a playable character loses all hit points, they faint; if all the player's characters fall in battle, the game ends and must be restored from a previously saved chapter, except in specific storyline-related battles that allow or force the player to lose. Between battles, the player can equip his/her characters with weapons, armor, helmets, and accessories that provide special effects (such as increased attack power or defense against magic), and various consumable items can be used both in and out of battles. Items and equipment can be purchased in shops or found on field maps, often in treasure chests. By exploring new areas and fighting enemies, players progress through Chrono Trigger's story.
Chrono Trigger uses an Active Time Battle system—a staple of Square's Final Fantasy game series designed by Hiroyuki Ito for Final Fantasy IV—named "Active Time Battle 2.0." Each character can take action in battle once a personal timer dependent on the character's speed statistic counts to zero. Magic and special physical techniques are handled through a system called "Techs." Techs deplete a character's magic points (a numerical meter similar to hit points), and often have special areas of effect; some spells damage huddled monsters, while others can harm enemies spread in a line. Enemies often change positions during battle, creating opportunities for tactical Tech use. A unique feature of Chrono Trigger's Tech system is that numerous cooperative techniques exist. Each character receives eight personal Techs which can be used in conjunction with others' to create Double and Triple Techs for greater effect. For instance, Crono's sword-spinning Cyclone Tech can be combined with Lucca's Flame Toss to create Flame Whirl. When characters with compatible Techs have enough magic points available to perform their techniques, the game automatically displays the combo as an option.
Chrono Trigger features several other distinct gameplay traits, including time travel. Players have access to seven eras of the game world's history, and past actions affect future events. Throughout history, players find new allies, complete side quests, and search for keynote villains. Time travel is accomplished via portals and pillars of light called "time gates", as well as a time machine named Epoch. The game contains thirteen unique endings; the ending the player receives depends on when and how they reach and complete the game's final battle. Chrono Trigger DS features a new ending that can be accessed from the End of Time upon completion of the final extra dungeon and optional final boss. Chrono Trigger also introduces a New Game Plus option; after completing the game, the player may begin a new game with the same character levels, techniques, and equipment, excluding money, with which they ended the previous playthrough. However, certain items central to the storyline are removed and must be found again, such as the sword Masamune. Square has since employed the New Game Plus concept in later titles, including Chrono Cross, Parasite Eve, Vagrant Story, Final Fantasy X-2, and Lightning Returns: Final Fantasy XIII.