1:headshot.pk3 - simple realisation of headshot. Try to shoot into imps heads and they will die quickly.
2:laserrocket.wad - the rocket launcher alt-fire can shoot laser-homing missile, as in Half-Life 1
3:lasermine.pk3 - the laser mines similar to ones from Half-Life 1 (slot 8) (using 3d models)
4:grenade.wad - try to type "summon GrenadeLauncherMarine" in console. The summoned marine can shoot grenades exactly into small windows and barriers.
The mods are mostly designed to learn some interesting features from source code.
Screenshots:
This one is the most interesting IMO, as far as I know no one else has been able to get an actor to accurately fire a projectile and account for the effects of "gravity" on it. I'll have to look at the code when I get home.
