Lots of tuts out there for weaps, too. Most important, see https://university.hl2dm.community/hl2dm_101.html or google for each weapon's and alt fire's damage, fire rate and splash (and calculate duration for:
-each weapon's fire: time to fire one round or one item, depending on the weapon
-each alt fire
-each weapon's empty: time to fire one whole clip
-reload
-weap switch).

Depending on these factors and the (*) below, u must learn to choose best weapon in each situation.. Or most fun weapon if you're in the mood. BTW, you can actually do a lot of kills with melee if you have the moves, right distance and some practice with moving, timing and calculating the enemy's rounds (phew!).
Approaching and cornering sometimes intimidates the opponent in missing his shots. Plus he's gonna reload at some point! Melee do more damage than u think. I'm talkin bout cornering a camper and clubbin him to death or spawning with defaults and outweighing a rifle with your pistol if there's no time to cook a nade.
AIM FOR HEAD (2nd rule of dm; the first one is: KEEP MOVING). Shots to the head do 3xdamage than normal ones. And pistol does 2xdamage than smg and has a hell of an accuracy compared to other hitscan weapons (magnum has the highest), you just have to clickity click fast.
OK, back to those of you who hate melees and want quick kills. JK

Offtopic: While spam has many meanings, such as to use something in large amounts either multiple projectiles (an orb, smg nade and prop from afar while aiming with mag in real time) at once or in rapid succession, it's also used to describe alt fire even in the amount of 1. There's power in a name. Yes, spam is shorter to say sometimes than alt fire, but when you only mean orb and smg nade, the correct term is alt fire, and thus it strips away the 'dirty' view of it, the scrub mentality.
Ontopic: Alt-fire is more reliable since it has less variance than aim and can be used from behind cover. In general alt fire, as well as nades and rpg, when used as spam it/they can also be utilitary. Besides prefire and noise to mask own sounds, it can also be used as wallhack (orbs), zoning, smoking enemy out, coverfire, checking where enemy is, diversion, establishing dominance. Plus a well timed smg nade can nullify enemy nade. Smg nades, as well as nades and RPG, can also be used as a form of CC (crowd control), since a well placed smg nade can knock up, knock back or push the enemy to the side which makes it for an easy set up for your next shot, be it mag if from afar, or shotgun if medium range/up close. If done right it can also knock enemy to the side and off their aim if they have a specific/constant aim rhythm and you interrupt it before their next shot, it could count as a form of dodging. Alt-fire is chock-full of utility even when used as a singular quantity.

• Always be ready to switch to ggun (have at least one key for it and the prev weap key);
  
• QuickGrab! Check it out in my Gameplay Training guide linked at the top and also the examples in this vid:
  https://youtu.be/4QfnpnwkPyQ
  
• while trying to catch stuff, walk towards the object/nade/orb and aim with ggun (imagine someone throwin a fast ball at you in real life.. you'd run for it and spread your arms towards it, right?).
  
• Another catching strategy is to click alt fire many times n fast, then throw back the object after aiming OR shoot it many times n fast
  
• [A nice exercise to make ur attack faster is to take a blade, shoot it in a wall at different distances and then take it back, as fast as you can; this right click (whether its catch or simply pick up) must be followd quickly by left click if enemy is still in your range and you're fast enough]
  
• Crouching sometimes helps cus your hitbox is just smaller and more chances of aiming in the right place and catching it, instead of standing up and have 3 huge blocks: legs, torso, head that can be hit
  
• Always expect a return! No matter what you throw (object/nade/orb), it can come back at you
  
• Unproved theory: use something similar to strafe jump theory and the object will have more speed and travel further, just like you would after a strafe jump; or shake mouse, throw prop and then strafe jump
  
• BUG: double right click and hold for silent object carry

attack mode: sprint fwd, fire, sprint back, or click like a madman if enemy's trapped or bit confused and not running away; be ready to change course as he sees you coming and try to get behind him but still attack while doing so (from aside or behind him)

• longer range for sprint fwd, fire and sprint back
  
• attack, retreat, no madman clicking, avoid jumping

• defense mode: let him attack and hit him every time he comes at you; if he tries to get behind you, strafe and dont let him, but attack (a sure hit, he might not be prepared and miss a club but you won't miss); if he tries to sprint jump at you, meet him half way or move back a bit and then attack (same thing, he's surprised and u definitely get a hit)
  
• another strategy: imagine a non-static wall between you that you're defending with the range of your melee whenever he tries to cross it, this involves lefty righty mostly
  
• myth maybe: if the swing is a bit longer (move player model on diagonal), bigger chances of a hit
  
• understand and adapt to whatever style you meet, either learn it and do the same, or counter attack the style

• Aim for head :D
  
• Strafe aim, circle strafe:
  • Strafe aim is where you actually aim with strafe keys mostly/only.
    • Keep mouse at head level (without moving or moving just a bit), move lefty righty and shoot when enemy is in range. Good for any distance and you also evade shots!
      
    • If you strafe too much to one side (let's say left) and miss the center spot, you can correct with a slight mouse turn (let's say right) or keep on strafing
  • Circle strafe is any kind of circle you do near the enemy, using mostly strafe keys.
    • As seen in CS, when you have aim locked at players head (with pistol, smg, ar2) or just want to get behind the player to evade his shots, you do a circle around the enemy with strafe keys while still aiming and shooting at the enemy.
  • Also, any kind of circles and unpredictable moves are welcome (like stopping in the middle of a predictable strafe jump), like the following:
    • imagine a circle and you and the enemy are at the opposites (the line between you is the diameter), you travel one half of a circle and shoot when you're right in front of him - strafe aim and circle strafe combined

• Switch weapons at reload OR
  
• Reload behind enemy or on one side of him, to avoid taking shots
  
• Slicing (the pie): is basically when you turn corners slowly/carefully, checking if it's safe inch by inch; this can also be accompanied by shoot/spray if enemy went right behind that corner or you know is waiting for you nonetheless
  
• (there's also Peeking, for general gameplay: peek behind corners for long corridors at the end of which enemy might be waiting with zoom on, so better do it fast.)
  
• Shoot someone starting a strafe jump, at an angle that kills their momentum, not boosts them.

• 1. 2 single barrels do more damage than 1 double barrel (therefore in theory 6 singles do most damage, 3 doubles do least damage)
  
• 2. aim for head, even if the spread on this weapon is bigger than of the others
  
  • if enemy is moving a lot in front of you, (this works better in lower grav I think) you can also crouch and aim up or jump and aim down so a bigger area of the hitbox gets shot, besides the head
• 3. The b-slap: more of a punch than slap, should be used when dealin with hoppers, jumpers, players that tend to move 10 times more than ur average player
  
  • the shot consists of a small-medium mouse curve from any direction to any direction (following the jumper) but the actual fire must come at the start of the curve
• 4. I go fwd and shoot, then retreat then repeat these 3; sometimes even in a circle, not just on a straight line, sometimes in zig zag; specially against someone also having shotgun, this assures maximum damage inflicted, minimum damage taken
  
• 5. aim/wait before shooting in case enemy ducks behind a wall, don't shoot 3-6 in a row

• Never underestimate the shotty. A good shotty does aprox 9-10 damage per pellet (see this figure in tsgk consortium - which isn't quite trustworthy - in the Weapon Stats section); beginner-average is below 9; 11 is extraordinary; anything above 12 (I once reached 11.7 but didn't check that in last few months) is shotty script, spread cheat, aimbot etc
  
• Use mostly singles for long range, or just other weapon, and mostly doubles for close range. Any combination can be tried though til you reach a successful strategy, like starting with 1 single when suddenly spotting enemy and not sure of his direction or location, to take the edge off and not lose a full double in case of miss, followed by a strong double when being surer of your shot.
  
• [Best damage is 2 doubles killing 100+200 :) Once you reach that, you're in shotty heaven. For training, I use the upper part of dm_killgardens_v1 without the props cus map has 3 super chargers.. and low grav which makes people fly farther and prettier hehe]
  
• If you fire it but switch wep right after and don't let the cocking animation go through, next time you switch to it you won't be able to fire it right away, it will play the cocking animation first.

(myth?) if enemy is standing right in front, use the floor - if he's crouching, standing or jumping, more chances of getting him
The crossbow imo is about learning how your enemy moves in order to guess his next location.

• When cooking nades, set them to explode above the enemy's head so they can't catch them. In the end any position is ok but with lots and lots of training. This is the first and easiest thing to learn, next to sprint jump, but the hardest thing to master, imo.
  
• More importanly, unpredictability is also needed, like staring at something else while cooking it, then suddenly changing direction and throwing it towards the real and unexpecting target.

• Have tracking device which is stronger after a bounce than after a simple release, so first shoot at floor, walls, ceiling somewhere in the middle between you and the enemy. Try to do not so obvious walls. Experiment. Have fun. For instance the floor might be the closest surface, but a faraway wall or a tall ceiling can prove to be more efficient 80% of the time and a good distraction 20% of the time as you can shoot the enemy for free while they have their ggun out. Some angles might be counter intuitive but as long as it's still aimed at the player even with 1 to 4 surfaces between you two, or in a small room, the tracking device will, well, track, and the counter intuitive part will work FOR you as the enemy will have a hard time guessing where to aim to try and catch your orb.
  
• The tracking device can also get stronger after 1 kill so in FFA make sure you hit a more predictable player first, you will notice the orb might not continue in the initial direction, but even return, at sharp angles, to get victims close by.
  
• The orb's tracking device also acts as an aimbot for the player trying to catch it. Just aim towards the wall or surface that looks like the enemy is about to use, with the reversed angle calculation.
  
• You can also dodge it AFTER its tracking device reset on the latest surface.
  
• You can't fire an orb from the AR2 if you are currently in the ammo reloading animation, so keep a few bullets in there if you want to use it.
  
• Can be used as your own cover fire.
  
• Orbs can be used as wallhack. If an orb changes direction more than anticipated, it indicates enemy presence. If enemy makes ggun noise, or even catches my orb, enemy location updates with more accuracy. And if they do not immediately release the orb, I now have a walking wallhack.
  
• Simply throwing one out there at random though is waste of resource, or might even get you killed. How? Enemy can return it, or it can hit a nearby exploding barrel, or set a prop in motion and cause you to suicide. Therefore a mistake, usually. Unless you do it with at least the purpose of experimenting with new angles.
  
• Be mindful when picking up either ar2 or orbs then switching weapons and having a fight later on, as this game does not display all your inventory at once and you might die without having fully utilized them.
  
• Orbs are weak in open areas and super wide open maps. They are strong in close quarters and rooms. If you are trapped in a room, best bet is to walk or run backwards to nearest exit while trying to catch incoming orb. Do not sit in corner, that only works sometimes. Position yourself in wider area rather than in small room when you know enemy has orbs. Punish with orbs when enemy is in small room.
  
• Be mindful of the deadly charge up time. It can mean death when done right in front of the enemy while walking in a straight line, sometimes charging behind cover is better, or simply priming it is an option. Or using more than 1 wall between us and the enemy.
  
• You kill someone with orb, you don't get their weapon.
  
• Orbs can be used to smoke enemy out, or check where enemy is.
  
• They are the biggest counter to RPG.

https://youtu.be/wZzoGLaYpqQ

Orb kick in equidistant system:
https://youtu.be/7uzCqEe0WEM

• after alt fire from ar2/nade, switch to ggun and as soon as orb/nade and ggun is out, shoot! They travel further and faster and are harder to catch.

• mouse1+q/g, q/g, mouse 2; movin fwd also helps. sprint jumping and doing the yoyo upon landing and not at the beginning of the jump also helps a lot. cus the obj isn't thrown up, but down on the ground and if u drop it, it just repels n it's easier to catch.

• 1. the oldest and most unuseful: throw a slam on floor, laser side down, sit on it while looking down and shoot xbow in it - slow bolt;
  
• 2. double slam (almost! impossible - https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=73927627 lol - after ob update, still present in mods), kinda low: better stay a bit to the side for this: look right at your head level, now lower the view just a bit and plant first slam; double q (last weapon) and look straight at head level and plant second slam over the laser of the first slam; retreat fast!
  
• 2'. theres actually another way where u do a short line slam, but have to stand right in front so it's kinda dangerous
  
• 3. dissapearing slam: plant one and shoot it with ggun (gone after ob update)
  
• 4. far slam: u pretend to plant a slam anywhere, even on floor, crouching, doesnt matter; but u see laser coming out, hear the sound and click for planting (I noticed the click is optional, the wait as it opens up and is 'at ready' is more important) and switch to dif weapon right before planting so it doesnt plant; now look anywhere in a 3, 4 square radius from ur head and switch back, it will automatically plant; works for under objects, stairs, hard to reach places, and for drawing live names lol https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=123362107

• if you open them and walk away, you still get the ammo in inventory
  
• if you use weapons like explosives to open them instead of pressing USE and then walk away, you still get the ammo if you switch to crowbar fast enuf (apparently xbow works, too, from a distance; any projectile with a delay long enough to switch to crowbar)

Since RPG works better on top of a surface than on a wall or ceiling, the accuracy increases if you get to higher ground to better see the top of the surface.
After 1 mag/xbow hit, switch to something faster and less expensive, if you're sure the enemy is very weak now. shotgun mainly or smg nade (others prefer to spray).
The most common combo is smg nade + shotgun. This is because the smg nade has a tendency to knock enemy up, while shotgun has a tendency to knock enemy back, and you don't want that in open areas. Shotgun can be a good opener/lead if stunning someone next to a wall or killing their momentum at the beginning of their strafe jump.
If xbow doesn't hit, still switch as it's like the slowest reload in the game. If you insist on using xbow after a miss, at least duck behind cover if there's any around.

• Almost all weapons, including firearms, this being more useful on mag, can be silenced if u do click, flashlight, click, flashlight, fast enuf
  
• Or fast switch to ggun after 1 shot

Small rant: Why gather everything if you won't use it? You're just making noise. If you want to deny enemy of resources, at least dump some smg nades or orbs to cover entrances. Or even throw them randomly so you can keep gathering to deny resources. End rant.
Your lead weapon is the best weapon or altfire in your inventory at any given time. This is what you walk/run with, in preparation of a new encounter. You want to start a fight strong and not die with 3 smg nades in your pocket. So lead with xbow, or smg nade, or orb, or mag, then see previous section 'Weapon combo'. Xbow trumps mag. Doesn't mean you need to travel across the map to get that xbow, whatever you have strongest at the time works. Why not rpg? You have to be absolutely certain you won't get one shot at close range from around a corner.
DO NOT initiate with a long range shotgun shot the second you see an enemy that's miles away. It's pointless and sometimes worse than no shot. You do negligible damage while giving away your position and possibly setting yourself up for an ambush/prop-to-the-face if you choose to chase. Or they might 180 no scope mag you, and at that range, shotgun vs mag is an exchange you do not want.

See 'Combinations' section at https://university.hl2dm.community/hl2dm_103.html

• Always watch your enemy, know where he is (or at least know where he's not so you can figure out where he can be) and what he's carrying (weapon inventory/health/armor). Watch his actions in a close combat, also.
  
• If at one point he starts running away, or backing out/hiding, switching weapons out of dispair (which weapon?), if there's blood after a certain shot, if he's pushed back by a shot etc! All these are signs of his health dropping which will help you decide what weapons you should use.
  
• Even though you died first, attacking him immediately after respawn is not always a good idea (also depends on item placement and amount); he might be weakened (or not) but he also might have a better weapon :)
  
• Following a fleeing enemy is often a bad idea as he can suddenly stop and turn with a shotgun hs blast, or after a corner turn you can be taken by surprise and be killed with well anything, specially a surprise prop (he can also be crouching behind the corner and get you from behind after you pass him haha) and if you must follow, do it at your own risk using also the slicing technique.

Last edited on: 06-28-2024, added RPG tip in OTHER.