3 Quick Opinions:
Main Menu lacks professional, slick, high-quality appeal. Way too much clutter - Needs to be minimalistic and ooze of quality. This it does not.
Difficulty Settings: A user should be able to quickly, with one mouse-click: Select an easier / harder difficulty.
Terrorist Hunt Mode: Hard for me to fathom why a game like this would not deem it almost an automatic - to include quite simply, a "terrorist hunt" mode. User should also ( with simple mouse-clicks) select amount of enemies in such mode.