My second criticism is that the later levels, when you get to take on the aliens in their own dimension, aren't as good as the earlier ones in the Black Mesa complex. But these are relatively minor points. Once again, Half-Life 's designers have come up trumps with a great variety of weapons, each with their pros and cons, with which to dispense death to those who stand in your way. Early on in the game you'll pick up a crowbar, which can be used to bludgeon your opponents, or to open crates, smash air grilles, break windows, etc. Much of the scenery is interactive, and the crowbar is usually a good choice with which to 'interact' with it.
Crowbar has to be the weapon of choice.
Next up there are two different pistols to collect. The 9mm is fairly puny, and not much use once you've found something more powerful. The submachine gun is a cracking weapon with a high rate of fire and an infinite range. The perfect introduction to a crowded room. Next up, the shotgun, which I have to admit to being a little disappointed by.