The basics of Blood Money are similar to past entries in the series; each mission is framed around the killings of one or more individuals, which the player character (Agent 47) must accomplish. Standing between him and success are armed guards, security checkpoints and other obstacles. The player guides 47 through the game's levels with the help of a satellite map which can be queried at any time. The map indicates the layout of each topographical area of the level, the whereabouts of 47's main targets, and other CPU-controlled characters. In order to carry out his mission, 47 may use any method at his disposal to eliminate his targets, regardless of witnesses or excessive violence done to bystanders. Not only rewarding stealth over bloodshed as is traditional in the series, Blood Money includes features that directly penalize the player for making too much 'noise'.
Many new features were introduced to Hitman: Blood Money. These include the capability to climb through more obstacles, improved unarmed combat, the ability to use an NPC as a human shield, improved character animations (example - face, eyes, etc), a new game engine and the ability to upgrade weapons and equipment. However, only five of the featured weapons in the game, as well as assorted pieces of equipment such as bombs and armor, can be upgraded. Every level contains some sort of method to make the target's death look like an accident; for example, tampering with someone's grill to make it explode when they turn it on, to rigging a chandelier to fall on a target, or the target 'accidentally' falling off a balcony. There are also improvised weapons, like a nailgun or a pair of hedge clippers.
A gameplay feature new to the Hitman series was also added, the "Notoriety" system. If the player, during a mission, kills innocents or civilians, gets caught on CCTV or is witnessed committing murder, Agent 47's notoriety will rise. Conversely, if the player executes the mission perfectly with none of the aforementioned events occurring, 47's notoriety will be minimal. The higher Agent 47's notoriety is, the easier it will be for NPCs to identify him. Players may use the bribery system to negate accumulated notoriety. The notoriety system is not enabled in "Rookie" mode, which also allows unlimited saves and a lower level of general difficulty.
When each mission has been completed, a newspaper article is displayed regarding the hit, in which the content varies depending on the investigation results and the player's notoriety. It will detail the weapon most frequently used, how accurately it was used, the number of police, security, and civilians killed or injured, and if there were any witnesses. Any injured people will be counted as witnesses. Depending on how many witnesses there were will affect your Notoriety. Sketch drawings are also sometimes visible of Agent 47's face, which grow progressively more accurate as 47's notoriety grows. The article's title relates to the player's mission rating. "Silent Assassin", in which you assassinate the targets as cleanly and quietly as possible, and draw no unnecessary attention to yourself (blow your cover, leave no extra bodies, etc.), is the best rating possible on all missions.
Blood Money also improved the melee weapons system, allowing the player to lethally throw certain weapons at NPCs (i.e. kitchen knives, stilletos, etc.) Once thrown into anybody, however, the weapon cannot be retrieved.
Blood Money also introduced the concept of rival assassins to the storyline. The developers created the Mark Parchezzi character as a sort of foil to the character 47, for he is "everything [Parchezzi] is not." The other "lesser" assassins were there to prove more able adversaries than "drug dealers or [similar adversaries]."