A solid tactical game with some strategy involved. With your addiction growing like the plague you're fighting.
The campaign can be huge or short and sweet dependant on start choices and provides for a very long and varied game, each one is randomly generated but this can also throw up anamolies which provide impossible to very easy and everything in between campaigns.
Mission types are also varied from facility captures, rescue of key scientists and personell to all out
search and destroy with each mission zone being randomly generated from dense city streets, bustling factories to sewers and some exotic locales in later stages of the game.
You are also charged with holding key facilities throughout the city and loss of some of them mean game over, this is the most tactical part of the game and you must be aware of the plagues spread throughout the city and try and ensure the area around them is kept clear of infection or you can be attacked or worse, engulfed by the plague growths.
The Faithful also start with bases which can be attacked to hinder their activities or avoided for a certain time untill the campaign progresses and you're forced to act on them.
Upside -
8 Specialist squadmembers from super strength and armour to forcefields and camoflage which gives varied playstyles but can lead to attachment of favourites. All soldiers recieve experience with which stats and abilities can be improved by choice. A good point to this is that it's mission kill and success based rather than per soldier, so if you lose a favourite or have neglected your squad then you can still train in later parts of the game.
Also every soldier including the first 8 super soldiers can acquire a very varied host of mutated powers after certain exposure to the virus later in the game. Infection takes them out of action untill the mutation reaches maturity and can be controlled. This brings a 'lot' of options to their abilities and further playstyles.
There is also weapon specialization for other squadmembers which means they are viable and sometimes essential if one of your unique soldiers bites it permanantly or you need that heavy gunner to take down a titan monster or sniper to assassinate key leaders of the cult.
Recruitment is also mainly done through search and rescue operations and is very dependant upon your speed and efficiency in rescuing them after mission starts and before they are over run and killed by the Faithful. Friendly troops are extremely weak before being brought in and given armour and weapons bigger than pistols.
There is a lot of equipment options, even from the outset. Including pistols, smgs, mgs, heavy mgs, grenades, rockets, deployable sensors and sentry guns, armour, meds etc. All with full descriptions of origin, damage, capacity, weight. This also affects how much each squad member can take into battle and it's not uncommon to have to scavenge weapons/ammo from dead Faithfull or search points to replace some of your large weapons from the cult of the plague. This becomes somewhat harder in later game stages as you encounter more and bigger plague monsters and less Faithfull but equipment boxes are usually around with some holding very powerfull firepower.
Downside -
Only 4 squadmembers per mission and only 1 mission transport at a time which makes little sense and also limits the otherwise excellent co-op multiplayer and your response to multiple mission hotspots. Also as it can become very fast paced and hectic which a turn based or full pause option replacing the time limited pause for multiplayer would have increased multiplayer enjoyability.
Poor resource management requiring an awful lot of in mission scavenging in missions rather than production which although is not essential if you skip searching before leaving at the end of a mission too often then advancing through the campaign becomes increasingly difficult, even though this fits in partly with the story it hampers enjoyability. You can manufacture goods however it is done on a short supply method and all equipment ordered is dropped into the city zone and you must collect it via a mission. You can make multiple orders but the more you order the more capture facility missions are generated and the more dropzones you have to collect, although normally easy these can divert from more important missions.
Another downside to the scavenging is it also seems to be tied into the advancement of equipment which is done on a level based system going from weak to strong. Although this is good it would have been better suited to research or facility capture missions as most new equipment it seems, can only be manufactured once you have found at least 1 in a mission.