When you shoot a crossbow bolt into the ground, for two seconds (while the bolt is still hot) another player can walk over the bolt and jump when directly on top to be launched into the air. They will be pushed in the direction the bolt was facing at tremendous speed (2000+ velocity). Can't be boosted by your own bolt. The larger angle you can create without bouncing the bolt, the higher velocity you will be able to launch someone (so shooting straight down has minimal effect).

Drop a SLAM on the ground. Stand on top of it and shoot a crossbow bolt directly at it. If you detonate the same SLAM while a slow bolt is in mid air, it begins to drop.

(Explosive barrels can be replaced with any explosive prop)

Barrel yoyo
After you yoyo an explosive barrel, it becomes volatile and will explode upon contact with anything.




Barrel Spawn Explode
Using the gravity gun, launch an explosive prop in the air, and then blow it up in midair with any weapon. The prop will instantly explode upon respawn.





Barrel Tagging
If you punt an explosive barrel, you become its owner and anyone killed by it will count as your kill.







Barrel Orb
Orbing a barrel to explode it does significantly higher self-damage as long as the orb hasn't bounced. (???)

Orbit
You can make a rocket spin around a prop (must be a prop) infinitely. Shoot rocket to your side and then quickly move the laser to the prop.






Figure 8
Make a rocket spin in a figure-8 shape forever by shooting it in an open space and then aiming the laser at a wall. Different from "orbit" because laser is pointed at map geometry rather than a prop.





Slow Rocket
Rocket slows down significantly if it goes through water.

If you spectate while holding a prop in your gravity gun and then rejoin, the prop will not register any collision with your player model or any bullets you shoot (but still functions normally for anyone else). Doesn't work if the server makes you suicide on spectate.

When you phys_swap (default gravity gun bind) while holding a prop, a client-side bug occurs where the prop seems to be frozen in mid air until you switch back to gravity gun.

This is only visual, and in reality (server-side) the prop actually fell to the ground. If a prop is frozen and you quickly switch to gravity gun and grab a different prop, the two props will be visually welded together. You can fix the bug by finding and grabbing the invisible prop and you can prevent the bug altogether by binding instead of the default grav gun bind.

You can roll grenades through corners where two walls meet. You just have to be crouched and right click roll the grenade while aiming at the corner. If the wall is thin enough it will reach the other side, otherwise it'll just fall under the map. (Video shows aiming at floor corner but you can aim anywhere along the y axis)

If you hate sawblades, use your gravity gun, aim at a sawblade and quickly right click and left click it. It will disappear just under the floor. Ground must be flat and any material type a sawblade can stick into. You can also hold the sawblade in your gravity gun and flick downwards and shoot, but it's harder.

You can open an ammo crate from anywhere and receive its contents as long as two conditions are met. You have to be holding a crowbar and you have to damage the ammo crate.

You can simply whack it with the crowbar. You can shoot a crossbow bolt and quickly switch to crowbar. Toss a nade at it and swap to crowbar before it explodes. Etc.

You can run alongside a wall while looking at a certain angle to move much faster than you normally would. Walking speed is 190 but you can reach 285. Sprint speed is 320 but you can reach 480. Useful in tight corridors like top hall on lockdown. The exact angle is 8 degrees toward the wall if using forward and a strafe key or 53 degrees into the wall if just using forward. These numbers will be different if server has a custom sv_friction or sv_airaccelerate.

Grab an orb with your gravity gun and get a someone to tag it with their gravity gun. The orb stays in your gravity gun but now belongs to the other person. If a teammate tagged the orb, it will not kill you and you can use it to quickly move around backwards.

After firing an SMG grenade, you can switch to your gravity gun and hit it almost instantly causing it to explode. This will push you backwards and the effect can be increased greatly if you're in midair and already moving.

You can drop a plant pot on its side into a corner and crouch into it. If done right, it will spin in place and if you have "cl_showpos 1" enabled you can see your velocity increasing even though you will not be moving. You can then get another player to jump on your head and they will be boosted proportionate to your velocity. If you remove the plant pot once your velocity is high enough you can also boost yourself.

Hold down crouch, release it for a very short time and then hold it again before you fully reach the standing position. You will know it works when you are unable to jump. Client side (to you), it will look like you are standing. Server side (to others), it will look like you are crouched. Any good server has a plugin to fix this bug.

Used to be a few different ways to do this but engine updates over time seem to have caused older methods to become obsolete.

Apparently the SLAM's laser is only visual and the actual trigger activates slightly after the laser shows up. You can place a SLAM, bodyblock the laser, and move out of the way during this window and the laser will be invisible.

You can place SLAMs in slightly out of reach areas and even on players. Begin placing a SLAM and then quickly flick your mouse. You can also save a SLAM in this special state by swapping weapons just before you place it, and swapping back when you want to place.

When grabbing a prop with the gravity gun, instead of just tapping right click, double tap and hold right click for about a second. You'll still be holding the prop but your gravity gun will be silent.

You can either: 1) Flashlight as soon as you fire a weapon. 2) Switch to gravity gun (with previous weapon bind) as soon as you fire a weapon.

HL2 style ladders (func_useableladder) are prone to bugs and breakable. When you start to mount a ladder, an entity called reserved_spot is momentarily created until you are on the ladder, then it is removed. This also applies to dismounting a ladder but only at the top or bottom of a ladder where there is an info_ladder_dismount entity to transition to.

• If you die during this transition, you will respawn on the reserved_spot, and then the reserved_spot is removed.
  
• If you spectate during this transition, the reserved_spot will exist until you rejoin, after which you will respawn on it. While the reserved_spot exists, it will block anyone else from using the ladder.
  
• If you leave the server while your reserved_spot exists, it can't be removed (even if you rejoin, since you no longer have the same player ID number), and the ladder is effectively broken for everyone until map change.
  

Detonating a SLAM using its trigger is normal, but damaging it any other way does no damage unless standing directly on top. (intentional?)

If you were holding down an input key such as movement or sprint or crouch when you died, keeping it held down will not let you respawn regardless of the mp_forcerespawn setting of a server. Can use console commands +duck, +moveleft, etc. to simulate keys being held down but don't forget to -duck to simulate letting go the key.

Weird bug where if you hold down an input key while in spectate and join the game keeping it held, you become a very slow ghost. Doesn't work after you have died once. (???)

Very old bug that carried over from goldsrc engine. No idea how to consistently recreate. As long as a wall or playerclip isn't parallel to the x/y axis of a map (?), you can jump next to it at a certain angle and keep a movement key held to float.

If your hardware is strong enough and you pull too many frames, you end up with speedhacks. Fixed by lowering your fps_max.

Yoyoing or even simply resetting a grenade with a grav gun slightly grows the red glow sprite every time. If the sprite gets too large the server crashes.

If a prop is (accidentally or intentionally) blocking a player spawn and a player joins the server into that spawn point, the player will be set to the map's 0,0,0 coordinates instead. Only works when initially joining the server(?)

Combining 2 of the above bugs (corner nade + ammo crate bug) on dm_tigcrik_r2 for easily accessible infinite supply of orbs







Wallbug from previous section in action, initiated with either a hotbolt or plant pot boost to reach high parts of a playerclip







Wall version of hotbolt done in a co-op fashion to boost both yourself and a teammate








Shoot a bolt and suicide right after to pin your ragdoll to a wall