How fun could this possibly be?
For those that don't know, in the book it's basically a big room, zero gravity, varying lighting, and floating cover. First person shooter style and freeze guns. Don't get what would make this any more interesting than any other FPS with the gravity turned off. The strategy and techniques that made the combat in the book interesting aren't going to be able to be adapted very well. Lying prone and shooting, freezing your own team and using them as a shield, and complex organized assaults really seem beyond the scope of a game like this.
So how fun can an FPS be with it's only selling points being a single room with zero gravity and one gun?
If they do it this way, it could be amazing:
Make it like Undertow. Maybe 3D, although 2D would be a lot easier to pull off.
Aim with the mouse. Left click to shoot, right click to jump off of what you're standing on. Middle click to grab on to what you jumped to. Then you can move around the thing you grabbed onto(wall, asteroid, frozen teammate, etc.) with wasd. If you get hit somewhere other than dead center, it simply takes away a limb. Makes it harder to maneuver each time you lose a limb. Lose both arms, you can't shoot but you can still jump around. Lose both legs, you can't move but you can still shoot. Longer you hold down right click before jumping, the harder your jump is going to be, making you go faster. Win by getting 5 people to the end. If you don't have 5 people left it's a stalemate.
Would make for a great multiplayer game. Have two different modes, one where there's no respawn, one where there's respawn every 30 seconds.
Playing: Assassin's Creed, Call of Duty 4. Dracula X Chronicles, Contra 4