Technically a standalone expansion/ direct spin-off to Silent Assassin, Contracts is a dark follow up to the former game and easily the darkest game in the series. But it isn't flawless.
The story is disjointed and weirdly presented. It feels abrupt but still ideologically works within the game's themes of fever Dreams. It's a chopped up narrative that takes us into the mind of Agent 47. The overall writing is pretty good. The dialogue is well written, but the underwhelming and bad voice acting from foreign characters brings down the quality and impact of the overall dialogue.
The atmosphere, sound design and soundtrack is by far the best part of this game. For a 2004 game, Contracts has some of the most impressive sound design you can find in a game. It's punchy and adds to the grim and suspenseful atmosphere. The soundtrack is grimy and haunting. Far ahead of its time for a videogame soundtrack.
The gameplay and level design is similar to Silent Assassin with a few helpful improvements. Some unpolished game mechanics from Silent Assassin feel SO much more useful this time around. The AI has been vastly improved and the overall gameplay feels authentic and feels like what Silent Assassin should've been as a game. (Although, Silent Assassin still has the much better story)
