Entity: weapon_crowbar
Acquired: Chapter 2, A Red Letter Day
Damage: 10
Tips: First weapon you get. Tool of choice for breaking open crates until you get the gravity gun. Recommend for narrow vents — it insta-kills headcrabs.

Entity: weapon_pistol
Acquired: Chapter 3, Route Kanal
Damage: 5
Rate of fire: Low
Accuracy: Very good
Range: Pretty good
Ammo: 150 rounds; plentiful
Tips: Accuracy, range and plentiful ammo make up for its weak stopping power. Good weapon for exploding barrels. You used to be able to ‘charge’ the pistol by holding down both primary and secondary fire, but this was patched out.

Entity: weapon_smg1
Acquired: Chapter 3, Route Kanal
Damage: 4 per bullet
Rate of fire: High
Accuracy: Not good
Range: Short-medium.
Ammo: 270 rounds; plentiful
Tips: Poor range and accuracy, but shoots bullets really fast and ammo is literally everywhere. Fire in short bursts to keep it accurate. The alt-fire grenade is useful but don’t shoot it too close. Personal weapon of choice in the coast levels (because of the ammo crate on the buggy)

Entity: weapon_frag
Acquired: Chapter 3, Route Kanal
Damage: 125
Rate of fire: Low
Accuracy: Depends
Range: Medium — can be extended (see tips)
Ammo: 5; fairly common
Tips: Good for tactics; can scatter clustered groups of enemies or flush them out from behind cover. With quick reflexes, it’s possible to extend the range with the gravity gun — toss the grenade into the air, grab it with the gravity gun, and throw it further. (You can also grab other enemy’s grenades in mid-air and toss it back at them!)

Entity: weapon_357
Acquired: Chapter 4, Water Hazard
Damage: 40
Rate of fire: Low
Accuracy: High
Range: All
Ammo: 12; rare
Tips: Very rare ammo, so don’t waste on lesser enemies. Comes in very useful for the later City 17 levels. Careful with the recoil.

Entity: weapon_physcannon
Acquired: Chapter 5, Black Mesa East
Damage/Rate of Fire/Accuracy/Range/Ammo: Depends on whatever’s around you.
Tips: Primary fire punts stuff around, secondary fire picks stuff up. Pick up a crate and smash it against a wall. Grab a sawblade and chuck it at a zombie. Punt a broken-down old car into a Combine soldier. Use it to toss enemy’s grenades right back at them. Possibilities are nearly endless, and wait until you get into the Citadel…

Entity: weapon_shotgun
Acquired: Chapter 6, “We Don’t Go To Ravenholm”
Damage: 8
Rate of fire: Low
Accuracy: Poor
Range: Short-medium
Ammo: 30 rounds; fairly common
Tips: Best for close-range; it gets less effective the farther away the enemy is. Aim for the head. Use the alt-fire for a double-blast. Good spread; it's great for blasting zombies in the face. It’s slow to reload, so you might want to switch to another weapon rather than wait.

Entity: weapon_ar2
Acquired: Chapter 6, “We Don’t Go To Ravenholm”
Damage: 8/shot
Rate of fire: High
Accuracy: Medium
Range: Short-medium
Ammo: 30 rounds; fairly common
Tips: Has a bit more stopping power than the SMG1. Ammo becomes more plentiful in the City 17 levels. The alt-fire shoots an energy ball that vaporizes anything it touches—good for small clusters of enemies (and also poison-crab zombies). Watch for recoil—fire in short bursts.
Also, there is no such thing as an AR3.

Entity: weapon_rpg
Acquired: Chapter 7, Highway 17
Damage: 200
Rate of Fire: Low
Accuracy: Depends
Range: Medium/long
Ammo: 3; rare unless you actually need it
Tips: Keep in mind the laser-guidance system. Unless there’s an infinite rocket crate nearby, don’t waste the ammo. Also, when you do see an infinite rocket crate, you should be crapping your pants because you'll be fighting a big enemy soon. Also, it's handy for taking out the snipers in that one level.

Entity: weapon_crossbow
Acquired: Chapter 7, Highway 17
Damage: 100 (insta-death to human-sized enemies)
Rate of Fire: Low
Accuracy: Good; watch for gravity
Range: Medium/Long
Ammo: 10; not very common
Tips: Basically a sniper rifle that shoots red-hot rebar at enemies, so it’s pretty cool. Save it for long-range, don’t waste the bolts on lesser enemies, and use the alt-fire for scope. Remember that the bolts drop over the distance, so aim a little over their head for best results. If the enemies are running around, aim to where they’re going, not where they are. It’s also fairly effective against Antlion Guards.

Entity: weapon_bugbait
Acquired: Chapter 8, Sandtraps
Damage: None, inherently
Rate of Fire/Accuracy/Range/Ammo: Not really applicable
Tips: Possessing one of these makes antlions your allies rather than your enemies (in-story - getting it early via cheats doesn't work). Primary fire throws it at a target, while alt-fire squeezes it and summons antlions to yourself. The antlions will attack most enemies by themselves anyways, but it’s good for getting them to run through tripmines or around corners.
Later on, after you don’t have the antlions anymore, throwing it at a Combine soldier makes it flail around wildly for a few seconds. It’s not very helpful but it's funny to watch.