Simon sends word of a trailer for an upcoming Half-Life 2 modification called Off-Limits:

Off Limits will be a teambased multiplayer Half-Life 2 modification. The gameplay will revolve around two teams attempting to take out a small, agressive, playercontrolled alien. The vanguard team will start the round with the only gun that can harm the alien, the rogues team will see the alien's position on their radar. The team that kills the alien, wins the round.

Grab the trailer locally from AusGamers.

That looks like it will rule.