so, it turns out that my Half-Life map collection is too big (i am making it on scratch), so i had to split it into 2 parts (the HL1 portion and the OP4 portion). i've also considered doing Blue Shift and Decay (i have already done map screenshots for DY)
Black Mesa as seen in Half-Life: Opposing Force's first half! i've added numbers so that people who don't know this game like the back of their hand can find their way around.