I did that in the demo but without the flares. Backed up in the first room I went into and sat there with the thing beaping and me staring towards the entrance. I advanced a little firing widley towards the doorway to bait him out.
Then 5 metres, 4, 3...... WTF......2..... 1.....
SCREACH
*Turn around, **** myself at alien behind me, then die*
Uninstalled and went back to worms. Me = pussy.
You sir are hillarious

Oh man that made me laugh!