You move with the WASD keys, look around with the mouse and shoot with the mouse button; standard stuff. There's an array of weapons, all taken from the original game, including (of course), the crowbar which has become so iconic for the series. Gameplay is in general very similar to Half-Life; if you've played the original, you won't miss a beat. In a way, this is good, staying true to the original content. In another way, the game feels a bit dated. Apart from a few scoped weapons, there is no way to look down the sights of your firearms, something which you'll find in nearly every shooter today. The weapons fire quite accurately, but there's still an element of un-learning play styles which have been taught over the better part of a decade. Similarly, there is no regenerative health; this game uses health-packs and armor-packs (in the form of hazard suit energy), much like many games did in the past, and this makes you rethink your approach to taking out your enemies. Finally, a welcomed return to the run-and-gun gameplay of the past, giving up the standard model of cover-based-shooting from today, keeps you on the edge of your seat and keeps the pacing high.
The trusty crowbar is still your best friend
Gameplay is further enhanced by the various characters which inhibit Black Mesa's world. In quite a few places, you'll find NPC allies, and by pressing the use button, you can make them follow and assist you, to the best of their abilities. Security guards will shoot enemies and fellow scientists will help you open doors. If an NPC can't follow you to a certain point, a welcomed addition to the game is that they will often motivate why, and tell you to go on, rather than simply waiting in silence for you to return, like they did in Half-Life.
A scientist offers his help
Enemy NPCs include soldiers and aliens and have improved AI from that used in Half-Life, but still fall short of impressing. Very often, it seems the enemy's tactic is to run towards you and attack when you're in range. Soldiers will take cover if you engage them from a distance, but much too often, hiding around a corner will make them rush you, making for unrealistic fire fights which are more about emptying your shotgun as soon as they show up, rather than actually outsmarting the enemy.