Half-Life 2 facts

at start of Route Canals you need to get on train and get to other side, there have trigger that move you there, but it works one time so if you do this again you will die and fly to space.

in d1_canals_05 there's secret Combine Soilder, you can kill him using grenades if you're not cheating.

the Airboat and Gravity Gun not supposed to be at same time so if you cheat and get weapon the Gravity Gun will react to Airboat like for Buggy, but if you're quick enough you can get in there when you use Gravity Gun and you will fly and you can easily get Out-of-bounds.

you can see how Manhacks will sleep, to do it you need to destroy the camera and kill Metrocop before he ends pressing button, everything that will touch one of them will wake up.

some weapons (like Pistol, or SMG, or etc.) will move the object to you're way if you shoot at it in right direction.

at moment when you get RPG have some weird things, when you enter there for split second you can see RPG on floor before Odessa pick it up, and Odessa is having fake RPG that means it just Entity not weapon, and if you will move back when he giving an RPG in while you're in trigger you can see that RPG is spawns on floor.

Citizens can grab weapons on you're hands, if they are grapping it and you throw the game will crash, and you can trick them by moving the weapon away while they picking it up so they picking up they weapon that they drop.

every speedrunner skipping the place where showing mines i don't know what they are named, but you didn't know that after you did it the Citizens gonna go there and die.

some weapons will react weird if you hold right mouse click, like for Crowbar it will move until you stop holding right mouse click, for SMG because of sound the sound of shooting will cut and start again, for AR2 it will just stop shooting, for RPG the dot will not come back until you stop holding, for Bugbait it will cancel throwing until you stop holding, for Revolver the animation of moving the weapon will be same until you stop holding.

at fight with Dropship it have gun, the old idea was to make even harder that gun can rotate but now it just shooting when it see you, the gun was broken in 2007 to 2010 (i think).

when you stop driving in Buggy it's possible to die if you move back and being crushed by doors.

if you go to first level of Follor Freeman you will have no ammo RPG, this was made to not kill Snipers that easily, if you load level before you will not have RPG, and loading level after that level (first level of Follow Freeman) you will have RPG with ammo.

the boxes with ammo or health or etc. it not randomly, it will give that what you have low, like low batery or low health and etc.

it is possible to shoot NPC's grenades, but you can't shoot you're grenades.

at start of Highway 17, Valve knew that players will place something on Buggy, so if you place breakable thing it will be breaked, if you place non-breakable thing then it just gonna be deleted.

AR2's energy balls can stick to crane magnets, same to Grenades but sometimes they will go through it.

if you get on top of Headcrab and kill it you will die for fall damage, this is because if you're on moving thing it will move you, and using it you can use REALLY BIG boost.

everyone knows that Poison Headcrab can take damage to 1 health, but you didn't know that if you have full health it will deal 99 damage and using it you can get big boost! but in Source there's not every damage will boost you, like Fire not gonna boost you.

most of weapons can be reloaded fast if you looking at friendly NPC, to do it just reload then switch to previous weapon and then back and you already reload, this is because game thinks that moving up is reload animation, you can also shoot while reloading.

at start of Sandtraps there's house with Roller Mines that are breaking roof, when object going to there it will be have weird glitch like it will fly, you can also break it before Roller Mines do it but because it have 10,000 healths so it will take a long time.

well that was only 20 facts but i will add more facts later, and don't forget to hit like button! bye!