The comics were by Malibu, an outside company that just paid for the licensing rights to make comics based on MK and then proceeded to make up some characters of their own in order to pad out the number of fighters at the tournament.

Midway didn't create and probably doesn't own any of those Malibu Comics-only characters like Hydro, which is why they never use them in any of the games.

Although, Malibu went out of business and I'm sure nobody's ever bothered to trademark Hydro, which is why Tancharoen got away with putting him in MK Legacy.
Also, Hydro would have the same powers as Rain. You don't need two ninjas with water moves.

But Hydro is blue, and in MK changing someone's color makes him a completely different character.

Hey, Smoke's been gray, black, white-ish, blue, purple and red!

A lot of times in the case of licence spinoffs the owners(in this case Midway)use work for hire contracts that basically say that they own the rights to anything that's created for the licence(Mortal Kombat).

This means that Hydro legally belongs to Midway/WB.

No, no you wont...

I would like to see him down the road at some point. Or if he is even mentioned or referenced that would be cool.

a lot of times =/ all the time
→ Your theory is very possible.

I say we just stick with Rain.

I wouldn't have minded Hydro accompanying Sub-Zero to MK1 in this game simply as a NPC and then being killed but, its too late for that.

Yeah Hydro would be a replica of Rain but he might have cooler fatalities though.

I would love to see hydro and tremor in the new game

Although it is not necessary with the transformation of Smoke, the death of Sub Zero and Cyrax's defection, the Lin Kuei is only cibogue Sektor's important at a time it takes the robot and the ultimate consequences Lin Kuei is powerful, just Sektor not juz acolyte would not the threat he represents.

So either we add a new character in this paper (which can be Hydro) or robotiza an old character.

Maybe they can put an easter egg or something like that involving Hydro

The Elder Gods had foreseen the warrior Rain getting attacked by the Lin Kuei clan and being transformed into the cyber ninja Hydro. He is pitted up against the newly automated Cyrax and they begin to fight an oily battle. Eventually, it is Cyrax that will emerge victorious and finish Hydro with a fatality. The Elder Gods have spoken!

And so ends this tale of woe, as we mourn the loss of Rain and Hydro.

Maybe one day he will appear. Maybe...Hydro will be in the next game in Sub-Zero's place do to Subs being dead & in the Netherealm under the service of Quan Chi & Shinnok. Hydro comes in as a friend of Sub-Zero & to fight along side Raiden & the others against Shinnok.

Wouldn't mind seeing him in the next game, also we have Ermac and KEnshi (same powers) so Rain and Hydro can co-exist as well i.m.o.

They can. However, I always see it on this site about the constant complaints about how two characters who have the same kind of powers shouldn't be in the game. Such as Frost and Sub-Zero. Why have two characters that have ice powers be in the same game? That's the issue that would be going on.

And to be honest, I just really don't see a point in bringing him into the series. So he's made appearances through the comics and web series... You have Tremor, who's actually been in a Mortal Kombat game, Special Forces, and still has yet to make it to a spot in the roster for a Mortal Kombat game.

Mhm kinda get the arguement for why would you have 2 characters with the same abilities, I just htink if done correctly, I see no reason why not, could actually add depth and story and even gameplay to them.

And yes, there are better / more unique characters to explore first, like for instance Tremor. (another fav of mine)

MK2011's Smoke pretty much did exactly what Hydro did, act as Sub-Zero's bro. Beyond that Hydro has no character, and thus, nothing that you liked about him (assuming you liked more than his outfit) would make it in to the games.