SiN

Sin introduced some new features to the first-person shooter genre, such as the ability to knock the weapon out of an opponent's hand and to take area-specific damage from enemies. Although driveable vehicles did not play a big part in the game, there are some sections and levels which require the player to drive certain vehicles, including an all-terrain vehicle, a patrol boat, a forklift, and a helicopter. There are three different types of body armor – for the legs, for the torso and for the head, with each of them depleting separately according to where the player is hit.

Computer terminals can be manipulated through a command prompt. Many levels have multiple ways in which to complete them, and actions can trigger changes in future levels. Some of these actions can force the player to go through an entirely different set of levels.

In the near future of 2037, the police force collapsed due to corruption and ineffectiveness against the rising tide of crime. Private security companies have taken the police's place, with some of them patrolling the streets like the former police, some in charge of protecting their employer's assets. The protagonist of the game, Colonel John R. ("Rusty") Blade, is the commander of one of the largest security forces in the city of Freeport, HardCorps. Prior to the beginning of the game, Blade is working to rid the streets of a potent new recreational drug named U4, which is rapidly gaining popularity in Freeport and is rumored to be able to cause genetic mutations to its users.

One of the companies that employs its own armed security forces is SinTEK, a large multinational biotechnology corporation specializing in medical and chemical research. The company is owned by Elexis Sinclaire, who took control of SinTEK following the disappearance of her father, Dr. Thrall Sinclaire, the company's founder.

Development started in 1997, on the Quake engine. When the Quake II engine was completed some months later, the developers switched to that engine.

A skeletal animation system was used for the characters.

Sin received above-average reviews, according to the review aggregation website GameRankings. While PC Zone gave the game a "Classic" award, praising its inventive level design and engaging plot, most other publications did not have such a glowing view towards it. Next Generation said, "while we feel the game may be a little light in the originality department, it certainly shines where it counts – gameplay – and [is] definitely worth your time."

One common complaint was the long load times, which measured in the minutes between each level, death, or quickload. With later patches, the long load times were greatly shortened, although compatibility with old save games was lost, forcing players to play through the game from the beginning or use cheats to progress to their previous point in the game. Another major concern was the abundance of bugs and glitches littered throughout the game. Some of the more widely reported bugs include a total lack of sound in the game, an end of chapter boss which could not move, a level on one path through the game not being finishable and general game crashes.