The gameplay follows the standard set by most first-person shooters with the player using an assortment of weapons. These include a crowbar, dual-pistols, a shotgun, a Thompson submachine gun (Tommy-gun), Molotov cocktails, a flamethrower, and a magical Ankh which can be used to wipe out many enemies at a time. The game does not come with any form of multiplay. To beat the game one must collect a number of vases spread throughout Matinicus Isle, each containing a symbolic part of Tess Conway's spirit. These vases also grant one-time per playthrough power ups. Some sections require the player to strafe, crouch, or jump. The game takes place on a rather large, nonlinear island, with no load times in between sections. Enemies defeated and items taken are permanent for the duration of a playthrough, with guarded weapon caches scattered throughout the island.

The player character is a college student out to discover the mystery behind a missing Egyptian artifact. The ancient "Water-Clock of Thoth" had been discovered by his Egyptology professor, Dr. Hargrove, but the artifact went missing soon after a visit by the expedition's patron, Tess Conway. Tess is the heiress of her family's estate on Matinicus Isle, where she keeps her friends, and pawns close by so that she might gain the true power of the Water-Clock. As the game progresses, the player finds out that Tess has used a number of people to gain what she desires, but at a price. Something went horribly wrong, transforming everyone on the entire isle into either restless ghosts, demons or the undead. In the opening cinematic on all versions of the game, Boldt Castle located on Heart Island in the Thousand Islands region of the Saint Lawrence River is used as the visual representation of the Conway Estate.

• Tess Conway (played by actress Lise Bruneau): Inheritor of her parents' wealth as well as the Conway Estate, Tess will stop at nothing to get what she wants. Obsessed with being young and beautiful forever, Tess acquires the ancient Egyptian Water-Clock in the hopes of using it to stop time itself. Tess keeps her most useful pawns close to her on the isle, nourishing them with food and drink long enough for her to have them help her fulfill truest ambitions. When at last she has the power of the Water-Clock within her grasp, she is murdered and subsequently activates the Water-Clock too soon in order to save her life and curse her killer. This action ends-up trapping all the people on the island, and the timing causes the experiment to go horribly wrong. Tess and her friends become restless spirits while the rest are turned into mindless zombies.
• Duncan DeVries: Tess' associate, and key to the black market. Duncan is an ambitious bootlegger trying to make a name for himself in the world of crime. His goal to marry Tess in order to acquire her property and wealth, Duncan does whatever Tess asks, in order to gain her favor. With a short temper and a broad mean streak, it's no wonder how quickly he turns to murder when he finds out that Tess has no mind for marriage. With her dying breath, Tess curses Duncan, and possesses his body with the vengeful spirit of Set (Seth).
• Byron: Tess' Archaeologist friend, Byron falls hopelessly in love with Tess, while helping her to decipher the instructions for the Water-Clock. All his efforts to woo Tess however, are futile of course, and the lonely Byron is reduced to nothing but another hapless pawn in the long run of things. Cleverer than anyone else, however, he knows the true power of the Water-Clock, which he keeps it to himself, carefully observing Tess' attempt for immortality so that he might learn from her mistakes.
• Mike: Duncan's rent-a-cop body guard, Mike follows Duncan around and makes sure everything goes smoothly. Officially the "guard" of the estate, Mike finds himself without much of a job to do most of the time. He appears only once by himself in the game to offer a quick warning to beware of both Duncan and Tess.
• Robert: Robert has been the Conways' official butler for years, and even goes as far as to reminisce over Tess and Lydia's adolescence together. Perhaps one of the game's only "truly innocent" characters, Robert laments over Tess' transformation after the death of her parents, and keeps a wary eye on Duncan, whom he openly distrusts. He is Byron's only friend and appears often to offer friendly advice on how to navigate the Conway estate. Robert dislikes what is going on but remains a loyal servant out of honor for the dying memory of the Conway family.
• Lydia Tweksbury: Tess' childhood friend, Lydia is kept on the isle for reasons unknown, though it would seem as though Tess gains confidence from being two steps ahead of Lydia at all times. Lydia confesses later in the game that she is sick of being in the shadow of Tess and works to bring her whole establishment down from the inside by leaking as much information as she can to Duncan. Both Duncan and Mike grow fond of Lydia during the course of the game primarily because she is physically attractive. All the same, she remains miserably trapped on the isle and spends most of her time drowning her worries in gin.
• Angela Conway: Tess' niece, this ghost of a young girl appears often in the game to spout cryptic poems, particularly in junctions in the hedge maze. Seemingly wise beyond her years, she understands what must be done and where to go and hopes that one can decipher her riddles in order to get the job done.

The game's original release came as a red CD. Players found a glitch in the game that happens in the clown stage.^{[citation needed]} The screen becomes pixelated and obscures the view of the entire area. The publisher allowed purchasers to mail them their red copy for a fixed version of the game, which appears on a black disk. Since so few purchasers sent in copies, the red version remains fairly common, but the black version is rare.^{[citation needed]} The 3DO Game Guru includes a save file patch which fixes the bug.

In 1996 Acclaim Entertainment acquired the rights to release three Studio 3DO games for the PlayStation, Saturn, and PC, including Killing Time.^[6][7] However, while Acclaim did publish the other two games for those platforms, they did not do so with Killing Time, even though a release date was announced^[8] and it was advertised in magazines^[9] and on the back of some manuals on games published by the company.

On July 23, 2015, ZOOM Platform announced the release of an updated version of Killing Time exclusively for their store. The update work was done by Jordan Freeman Group and published by ZOOM Platform and Prism Entertainment.^[10]

The game was also re-released onto gog.com on November 10, 2016.^[11]

The original 3DO release received mostly positive reviews. Critics for both Next Generation and GamePro praised the fast game engine and combination of intense first-person shooting with brain-stimulating adventure elements.^[12][16] GamePro also approved of the stylish visuals and music and especially the use of real-life weapons for the player's arsenal, though they criticized the need to use button combinations to change weapons or look up and down.^[16] Next Generation complimented the humor and concluded, "In short, Killing Time is the bastard child of Doom and 7th Guest, and it works."^[12]

The game was awarded the 3DO Adventure Game of the Year.^[17] In 1996, GamesMaster ranked the 3DO version 2nd on their "The GamesMaster 3DO Top 10."^[18]

• Killing Time at MobyGames