Cordon in S.T.A.L.K.E.R. - Shadow of Chernobyl.

Yay, correct. Either my memories are still good or yours are as bad as mine.

But it was indeed my intention. It may also be the only map layout I (kinda) remember from any game ever.

Ah, now we know where ID software cropped their cacodemon doom sprite from.

Doom

I have the map for the game hanging on the wall next to me, and it is very similar in a crude sort of way. Also, while Cordon is in Clear Sky as well, you get into the area bit further south, so I suspect you would have put something in between the safe area and the southern military base if that game was your intention.