This was my entry to the "DM2SP" competition (see
PlanetPhillip entry). It is based on my HL2DM map
"dm_balcony".
In this short rescue mission, you have to help Uriah, a Vortigaunt scientist, escape from a combine prison by guiding him to a teleporter. I had to use some entity hacks to get him to follow the player. You can command Uriah to stop or continue following you by pressing the use key on him (classic HL1 mode).
For the finale, you can use a bunch of friendly roller mines to set up a defense. Remember, the only way to destroy roller mines are explosives, to think twice before using grenades...