Cooking of grenades

Concussion grenades should be cookable in your hand instead of the current short fuse mechanic. Could be a toggleable fire mode, the secondary fire mode allowing for two clicks, one cooking and one throwing. Right mouse button would be the zoom key for both modes.

Grenades should be able to go off in your hands if cooked for too long, this could possibly also apply to gas and smoke grenades, allowing for "mobile" gas / smoke screens.