Instead of using say... a fixed round... maybe include an option to include a set minute assault mode. (this would be server selectable, or something) Where the game continues at all times, not round based.
General rules would be:
5 seconds until respawn after death
8 seconds of invulnerability (enough time to buy items, plus kill possibility of spawn campers) Players invulnerable would be shown as partly transparent.
For every 10 kills a team makes, they get a point. Every VIP kill gets 5 points, every escape awards 10. (plus VIP levels might be more popular with an "assault" mode, as it's sometimes irritating when the VIP doesn't listen and wanders off, a) the round wouldn't end, and at least the team can make up for the VIP being stupid by killing the opposite team. Every bomb planted gets 3 points with detonation getting 6 points. CT Defusal would earn their team 8 points (just sake of balancing, it's easier to plant and detonate as it is to defuse) Every hostage returned would bring a point, every hostage guider (the person who presses the 'use' key) killed will gain a point for the team.
New possible game modes that I think might be an interesting twist on the Counter-Strike universe would be multiple bombs with multiple bombing points. Or multiple VIPs (for the roundbased part of the game)
Allowing VIPs to buy ammo or other pistols can also help keep the CT team alive especially since a lot of people selected as a VIP run and gun instead of sticking together as a team.
Hmm?