Open world is like GTA. Crysis 1 isn't open world.
Ignore the trolls. Crysis 2 has more playspace than Crysis 1.
In Crysis 1 you had a huge area with 10% detail, with smallish bubbles of action like villages, with 60% detail.
In Crysis 2 each level starts and ends with (disguised) corridor bits where the game collapses skyscraqers and tells a story. In between these "corridors" is a huge bubble of action with 30% detail, and each bubble has small sub-bubbles with 90% detail.
Here's an example for one level in Crysis 2.
You start off in a skyscraqer which is breaking apart and shakey, with lots of explosions going on outside. You walk around corners and down hallways for about a second, listening to dialogue and seeing the pretty graphics.
Suddenly an alien ship smashes through part of the skyscraqer, metres from you. You fall to the ground and it's cool.
There's more story, and then you battle your way through a fairly linear carpark complex. But you have lots of toys to play with and styles to play. So stealth, loud, kicking cars, etc. You climb to the rooftoop of the complex.
-ACTUAL LEVEL BEGINS-
So there's a very big collapsed multi-storey carpark between you and your objective, diagonally. Each intersection is chock full of enemies and cars to drive. You have several distinct paths to choose from:
1. Sewers
2. Left side - Rooftops
3. Left side - Ground level
4. Right side - Ground level
5. Through the collapsed carpark complex. Yep. Through it. It isn't empty and inaccessible.
You can play each path stealthily, rambo-y, etc with toys to play with like mounted guns, cars to kick, cars to drive and ledges to jump on.
After taking one of the above routes you'll find yourself at 5 possible but very different angles to attack the objective-area from. You can play with stealth, rambo, etc. This particular area has several levels. Floor 2, floor 1, ground floor, crater. You can jump, climb and run your way between them.
So after shooting the bad guys you unveil a terrible secret and then fight your first alien. Good fun. There's a lot of jumping around. Then the level winds down to the story-based corridor finish again. You make your way up the street and see humans desperately battling with aliens. I forgot the rest
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An observation: Crysis 2 will have open combat no matter what. If you took the nanosuit 2, dumped it in CoD, made the AI competent, and made the surroundings interactive and physicalised you'd have a freeform game.
The nanosuit 2 feeds off your creativity.