Prototype 2 Geek
Prototype 2 is hands-downs the best melee-focused action-sandbox game on the market, though it incorporates elements of stealth and shooter well within it's core superhero-action mechanics. Think of Prototype 2 as Red Faction: Guerrilla, Assassin's Creed and your choice of the Hulk or Spider-man games all rolled into an infected zombie-flavored pie-shell. The Prototype 2content are: Gameplay Choices, Story, Collectables, Environment, and Achievements.
Gameplay Choices
The story may be linear, but how you fulfill your missions certainly isn't - in a given situation you have the option to sneak peaceably by in the skin of a soldier, use that stealth to consume every last enemy one by one, take up a gun and fight on their side against the infected, hijack your choice of tank or helicopter, or just tear the missile pods off of their sides for some heavy weaponry - all in addition to the main game play which consists of action-heavy combat with your choice out of five different weapon-arms, throwing cars, reflecting missiles with carefully timed blocks and eventually forcing some of the infected to fight on your side.
Story
Suprisingly good, the prologue in particular shines before the sandbox opens up and I personally ended up spending a lot of time searching out all the collectables - but you can hardly fault sandbox game for having a fun sandbox to explore!
Collectables
Surprisingly painless, the game incorporates a vague impression of collectable location on the map, as well as keeping track for you of those you've collected. This alone would be impressive, but more so is that collecting sets of collectables unlocks upgrades, somewhat similar to the Fallout perk system - you get a choice of various upgrades, from 25% less damages taken to getting more health out of meals or doing 10% more damage against military units ir jumping 25% further.
Environment
A particular improvement from the original Prototype is the environment - instead of one giant city, almost identical everywhere, the city in Prototype 2 is cut up into three sections, the Red, yellow and Green zones, each with a different look and feel to keep the game varied.
Achievements
Very easy overall, they should take no more than an estimated 16 hours and require little beyond playing through on hard(doable on your first playthrough), collecting everything and doing about half of a second playthrough.