This review has spoilers for the first Deus Ex game, if you care.
People like to say, "Invisible War is a good game, but a bad Deus Ex game." But they're wrong. 100% wrong, in fact.
Invisible War is a pretty good Deus Ex game. And a terrible video game.
I say this because the game offers up a reasonable facsimile of the Deus Ex formula you want, but everything is so botched that you no longer want it.
Going in, I thought the lack of skills and universal ammo would ruin the game's systems, but it turns out that the systems themselves are so pointless they ruin themselves. The only thing universal ammo does is make it so you never run out of ammo ever. That might be interesting if the guns had specific use-cases, but they don't-- once you get the sniper rifle there is no need to use anything else, ever. I also thought the changes to the augmentation system, this time called 'biomods,' might prove disasterous. The whole point in the first and subsequent Deus Ex games is that these powers are permanent choices you have to stick with, but in Invisible War you can respec your biomods at will. You can equip 5 biomods at once, but I found only three of them to be useful so there was little reason for me to even think about the whole system. And as a matter of fact, I maxed out all of my installed biomods, even the ones I didn't care about, before I was halfway through the game.
And that's another major flaw. The economy in this game is busted and everything is so useless that there is no reason to explore or strategize. As long as you are vaguely diligent in looting corpses you will never run out of ammo, so there's no need to go looking. The biomods are useless and easily maxed out, so when NPCs offer them up as quest rewards hours away from the end of the game it just seems pathetic. Ditto with weapon mods, the would-be second most important loot. You can install two mods per weapon, and since you should be using the sniper rifle 90% of the time this means roughly 2 weapon mods are of use in the entire game. I ended the game with about half a dozen extra of each individual mod. And just like the useless biomod canisters, NPCs thought I would love them even at the end of the game. At least they give you the option to turn down these rewards and instead accept money you don't need because the only shops sell nothing but biomod canisters and weapon mods.
Invisible War is kind of a shock to me in other ways since, while I am not at all someone who will enjoy a game purely for its story, it highlights how important narrative can be when in service of the gameplay. In it's own way the game's narrative style is mechanically very similar to the first Deus Ex in that your actions will affect the fates of characters. Characters can end up dead, assimilated by the borg, or whatever else because of the things you do. Unfortunately it's hard to care because there's no context provided for any of it. The two factions that lead you through the story, The Order and the WTO, are so hands-off and pokerfaced that the inevitable twists and conspiracy reveals are not shocking at all. As far as one can be concerned, both of those organizations are just a handful of annoying voices who yell at you over your radio, not actual factions you involve yourself in.
The reason the original Deus Ex's twists and consequences were so effective was because it spent its time building up context. Having UNATCO turn on you was a big deal because you spent upwards of three playtime hours working for them. Seeing the grey death being manufactured at Versalife was cool because it was set up 5-10 hours beforehand, and foreshadowed greater things to come. Invisible War just has a bunch of Checkov's Guns firing wildly into the air before anybody's had the chance to hang them up, and the audience is only made faintly aware of what a gun even is.
Wrapping up, the endgame is outright terrible. First off, the big final choice is whether you want to work for Evil Guys A, Evil Guys B, or Jesus Christ Denton The Hero You Played As In That Game You Loved. It's not exactly testing anyone's moral flexibility or philosophical leaning. Furthermore, they stick on you a nostalgia grab version of Liberty Island in which the entire Hudson River is frozen solid because they didn't want to program swimming. Liberty Island is full of armored trigens with rocket launchers. There are no ammo pickups anywhere and if you try to use melee the trigens explode upon death, killing you. It was a really fun time, and a fantastic way to cap off the experience.