If you could forgive mass effect, you can forgive the flaws in IW and enjoy this ambitious shooter.
Having said that, Deus Ex: Invisible War (IW) is in many ways the mass effect of FPS games. It's unique plot and interesting features are enticing, but often let down by some poor design choices and incompetent ai. It does many things right in the sense of interactivity, decision-making and morality, but ultimately lacks a great canvas to paint its picture on.
The game opens with an explosion of nanites that takes out Chicago. Within moments of the terrorist attack on the tarsus academy where your character is residing, he or she is transported to Seattle and awakes in the middle of another attack. From there on it's up to you to discover who was behind the attack and who you can trust as you are thrust into a world of conspiracy and corruption. Sufficed to say that everyone should be subject to your scrutiny, as even the people who have trained you have dirty secrets to keep.
The gameplay, like the original, is an FPS driven mainly by rpg elements, stealth and decision making. I will be blunt, the stealth almost completely useless and the enemies are so dumb that you rarely face an insurmountable obstacle. Most enemies notice you with relative and have no problem standing to take aim while you pump rounds into them. Granted that this was made in a time before cover systems, but the enemy has no concept of running, quick drawing or even shooting rapidly, and you can drop most enemies before then get to fire if you are accurate enough. In one situation when I had triggered an alarm, 5 soldiers in file charged through a doorway only to be picked off one by one by my shotgun.
Of course, you probably didn't pick this game up to see a revolution in ai. The enemies are dumb, but the decision-making is solid. Stealth maybe a useless feature, but biomods that you collect make traversing camera and turret-lined corridors a breeze. Weapons and your character's biomodifications can be upgraded with various abilities, making for some unique options. If you need to get past guards you can cloak, use spider grenades, go in guns blazing, or do what was popular in the day and crawl though many, many vents. You have dialogue options, which while not as good as Fallout 3, do ultimately affect the outcome of the game. You can befriend several organizations in the game to earn their trust or betray them. Freedom is the ultimate treat of this game, as anyone save for one instance can be killed, and nothing can stop you. Like Mass effect, the appeal is all in the freedom.
The game's aesthetics are old, but still relatively decent by standards. The cyborg race known as the omar vocalize with a disturbing and mechanical voice. Enemies cry that they've been poisoned when you shoot them with darts, and cry for you to come out and fight when you cloak. Robots notify you that they are damaged, or that they are engaging. The world feels cold and orwellian, as there are cameras and government guards everywhere.
While the game is ominous and the decisions you make do a great job in making the world feel alive, there are some flaws that the game suffers from. All the ammo you ever collect is pooled, a decision that makes the game more rpg oriented but less entertaining as it kills some realism. It's not a tedius flaw, but an annoying one since when you run dry with one gun you can't just switch to another. Also, the inventory system is atrocious. You can only hold a certain number of items on your hotkeys, and just as many in your inventory. The limit feels strange seeing as how you are training to be a super soldier, and can hold 10 medkits but can't carry an extra soda. It doesn't cripple the game, but it makes it frustrating to have to choose what to carry on to the next levels and what to leave behind. You are almost certain to be choosy about what's in your inventory by the end of Seattle.
The game, with side missions included, will take you around 15 hours to complete. There are multiple endings, but you don't have to replay the game to see them, just about the last 10 minutes of it. There is some replay value in trying new mods, making different choices and seeing how other dialogue options play out, but chances are once is enough for this game. That's sad to say, as it is an intriguing game that doesn't hit the mark all the time, but is close enough to it to recommend it to anyone that loves cyberpunk, dystopian universes and first person shooter roleplaying games. The game has soul to say the least.