make it so u have a dog sidekick but the dog dies and it's sad :( 

Though something like that would require something like Darkplaces, since MorphBall physics had to be nicely implemented like in the Prime games, and trying to emulate door transitions as connecting two maps together (while knowing two rooms are loaded, including the one the player's in, to, facilitate room transitions).
There's also how the camera works, you'd move around Samus with both directional keys and mouse, where the mouse is the camera. It still works like a FPS, where the character moves along the mouse, but when using directionnal keys the character actually turns to that direction, it gives a 3D Platformer vibe, combined with the character not turning if you move the mouse while standing still.
Also the character model goes transparent if the camera is too close to it. 

You have to eat the dog.

And then later you learn it had puppies and they're abandoned and you have to carry them with you. But you're really hungry.

If you go without eating then you get weaker and can't fight as well, but if you eat a puppy then it raises your sad meter.

If the sad meter is full then you don't sleep well, which makes you more hungry.

If you play with the puppies then it lowers your sad meter.

The puppies also need to eat; gibs. 

make it so u have a raccoon sidekick but the raccoon accidentally melts its cotton candy in a puddle of water and it's sad :( 

You heartless monster I hate that video and u just triggered me 

I'm offended. 

Can I make a serious observation that the existing "post some mapping ideas" thread should probably be changed into "post some mapping/modding ideas" because it's daft having two threads on basically the same topic 

Because 90% of maps released these days are also mods I guess 

What's next, merging the gaming threads? 

All the mods I can think of are probably need engine mods as well as QC.

Things like, custom particle effects.

Chains or ropes with physics.

A language to allow for more complex scripted events, etc. 

Oh, but those are technical modifications. I'm just interested in experimenting with gameplay. I don't intend on creating new assets or effects, unless strictly necessary. For example, if i wanted to do a Portal mod (which has already been done), i don't need any new things. I can use the lighting gun and the existing teleporter asset. 

Is something i always wanted to do, but i got some roundabout ways to achieve a similar end, so i do no longer yearn for it.

For example a trigger multiple that is only able to be triggered the second time you pass through it. 

Where you play as an arch vile and need to revive various monsters in certain order to solve puzzles and beat the map. 

On the weapon side, I'd like to see a weaker BFG blob as alternate fire of the thunderbold. 

That's a rocket launcher.

Quake needs fewer redundant weapons, not more. 

could function as the Tempest from Black Ops 3 - a sort of lightning-railgun that electrocutes an enemy, then that enemy acts as a lightning rod for a bit before collapsing, damaging other enemies that get too close.

Fun weapon. 

It would be stronger and slower than a rocket, splashing damage on its path. Not so strong as Doom BFG, maybe 3 rockets? Doom BFG shot damaged like 4 rockets, if I remember. 

The Doom BFG had one of the weirdest damage modes of any game. It's essentially an incredibly awkward shotgun:

http://doomwiki.org/wiki/BFG9000 

is the weapon you are talking about. Is like a weaker BFG, it just needs the tracking rays while flying to be a complete BFG. 

Is what i am talking about.