Hitman (World of Assassination Trilogy)

47's movement is practically silent even when running, except in Professional Mode where people will investigate footsteps. Running also isn't suspicious, so don't waste time going slower than you have to.

If you have instinct mode on, there will be a dot over people's heads that will see through your disguise.

A surprising amount of assassinations can be pulled off with patience and choking/neck breaking at the right time. This is often boring but sometimes the opportunity will fall into your lap.

Experimentation is good, doing levels over again and completing more challenges unlocks more tools, weapons, starting points, etc.

Most challenges don't require finishing the mission unless they explicitly state otherwise, meaning you can save, drop a chandelier on someone's head to complete the challenge to do so, then load your save without losing credit for the challenge. Doesn't apply to Professional Mode.

The game autosaves frequently which can be a lifesaver, but it's a good idea to make a manual save before you try something that seems risky.

Steal every tool, knife, can, soda, fruit, etc that you can. Many innocuous objects are actually keys to opportunities or interactions around the map.

All food- and drink-related costumes allow you to poison any food and drink without raising suspicion. Similarly, tech- and maintenance-related outfits often allow you to freely sabotage things.

Bodies found as a result of accident or poison kills don't count against your score, no matter how public their place of death is, as long as you're not directly seen causing them. This makes them great for Silent Assassin runs.

Fire extinguishers and gas cylinders can be used as "portable accidents" as deaths to their explosions will always be considered accident kills, allowing for "silent" assassinations even in public areas. Their explosions also open most doors.

Agility actions such as hanging from railings or climbing drain pipes are usually not considered suspicious, unless you're doing so in an area you're not allowed to be in. Getting around using ledges and drain pipes is especially useful in Paris.

While you can manually disable security stations, which control a level's cameras and store their footage, shooting them from a distance with a silenced gun is often much easier.

All default non-disguise outfits count for Suit Only -challenges, meaning you can (and probably should) do them dressed up as a clown or Santa Claus.

Game Modes

Contracts mode is user created stuff, it can be pretty fun, you can also make your own fairly easily

Escalation mode is just the same short mission over and over with it upping the ante each time like with additional targets, conditions (no non-target kills, hide bodies within a time limit, etc), or obstacles.

There's a console-exclusive set of missions called the Sarajevo Six that's basically an additional target in each level. The game recommends doing them after playing through and in order, mostly to avoid spoiling plot stuff. Watch out: the fifth is very difficult.

Elusive Targets: you are locked in once one target is dead or one objective is completed. Before this point, you can restart! Take advantage of this to learn the mission. Be absolutely certain before you pull the trigger!

Pro mode is unlocked after you've developed some mastery in a given main story episode. It's much, much harder than the main game, with new guards, cameras, mechanics, and combat is almost instantly lethal. The big change, though, is that players only have one save per run on Professional- and you must complete the mission to complete each challenge and gain Pro mission mastery and unlocks. Pro mode's rewards are 99% cosmetic, and are thus best left for after you've truly mastered the rest of the game.