Heres some great ideas:
Clouds into the game.
The game needs a little re-texturing.
Options such as Render distance.
You could swim under water also when you swim you can dodge bullets.
Make the health a little higher.
You could add a couple more explosives for example TNT C4 and others.
Running could be improved.
Could be possible if there's different modes like defuse the bomb.
You're character could speak in game voice.
Could be easier if when you press the crouch button it holds the crouching without holding the button when you press it again you de-Crouch what I call it.
[The end be sure add the ideas developers]