Gotta agree with the op about alien crush and crimson skies.

Someone posted Super Contra. I have to disagree, Plain ole Contra for NES is the best retro co-op of all time. 

Yeah, I could see that.  I preferred Actraiser though.

Haven't played the new Actraiser that released last year yet.  FF 14 has kept me from playing a bunch of games I want to try.  Have you tried the new Actraiser yet?

No I didn’t even know about it. Looks clean though. I don’t own a switch but I will play it if I get a chance. Would you recommend dark cloud?

Not sure about Dark Cloud.  I remember playing for an hour or so in a store demo back in the day.  It seems like 3D Zelda with the town building aspect of Actraiser.  If that sounds good to you, then I'd give it a try.

You, sir, won the internet! This is one of the first Mega Drive (Genesis' name here in Brasil) games I ever saw and it blew my freaking mind, mainly after years with the NES. I used to play this one so well that, when emulators became a thing in the end of the 90s/beginning of the 2000s, I would finish the game playing on the keyboard without deaths/continues. My son also plays it nowadays. An underrated, amazing gem!

I still go back to its soundtrack from time to time. I do recommend listening to the first stage's song (start of the video below) and then moving to the third one (Until the End of the Earth - 4 minutes mark of the video). How they overcame the system sound limitations is absolutely mesmerizing (remember: it was a MIDI only time back then).

Treasure of the Rudras - The final game that Squaresoft released on the super Famicom. It never got released in the West but there's a fan translation out there. It's often considered a kind of "Final Fantasy 6.5" and while I wouldn't necessarily go that far, it's a fantastic turn based RPG that looks stunning. The animations are almost of 2D PlayStation quality.

https://www.youtube.com/watch?v=83mH-xHeI5Q

Simon's Quest!!!!

And play it properly, meaning do not look up guides but figure out what to do and how by yourself. 

That would be insane. I remember leaving my Nintendo on overnight since we couldn’t figure out how to pass a section, and we stayed up late trying. 

Yep that definitely sounds worth it. As long as it doesn’t make me scroll through text every time I pick up a new item. 

WTH why?

It has a password system, it's just to go to the passage again the next day. 

I love that game and I personally think it gets to much shit either from people that have not played it at all or people that need handholding. I love that some NPCs give nonsense tips or that some NPCs straight up mislead you, you know like real people would. 

There of course are some aspects that is really annoying, like the text box at every day/night shift that you can't skip and takes several seconds to print out the text. Even if that gets old really fast the actual day/night mechanic is a good thing and Simon's Quest was one of the first (if not the first) game that had something like that.