RetroGaming

Oh, and sorry for so many responses, but I figure that posting these separately will let the votes give you some idea where to start.

The votes I've seen so far very much reflect the order I would try these games out with a five year old gamer.

City Connection, Bugs Bunny's Crazy Castle. While neither are co-op my mom and took turns playing crazy castle on the nes when I was a kid and we beat it. Core memory right there.

I think Tetris or Doctor Mario had 2 player modes but I'm not sure.

Does Sonic Spinball on the Genesis have multiplayer?

On the SNES, all of the games below have coop:

• Tiny Toons Wild and Wacky Sports - a collection of several silly minigames as some sort of tournament, with minimum scores that need to be reached. No direct violence between players, only cartoon shenanigans like falling down a cliff, snowballing after tripping while skiing, etc. (Maybe show the kid some of the old cartoons as well, if s/he enjoys, I'm sure the game will be more interesting to him/her)
• Super Bomberman - Might count as "violent", since you're bombing weird looking enemies, but it's a formula that rarely gets old and plays great as co-op. Your kid might enjoy 3 and 4 the most, with the variety of mounts to be had (if your rpi can run NeoGeo games, Neo Bomberman is also a great choice)
• Top Gear - Racing game with one of the best soundtracks in the console. Top Gear 3000 goes to space and has plenty of options for upgrading your car.
• Secret of Mana - Might count as "violent", especially as you start off with a sword and kill cute bunny-thing enemies. An action RPG that, once you get the 2nd character, it can be played with the 2nd controller. Drop-in/drop-out, so you can easily join and leave while your kid plays or vice versa. The same applies for Secret of Mana 2 (Seiken Densetsu 3)
• Magical Quest 2 and 3 - Disney games that are best when played cooperatively (the first lacks coop). Starts off easy enough and you get new costumes that give special powers, which help you out in the stages going forward. It's "Disney violence" how you beat most enemies (jumping on their heads, spinning them against one another)
• Kirby Super Star and Dreamland 3 - Both allow for a second player to join in and help. Dreamland 3 has a very unique and cute looking style.
• International Super Star Soccer - If you're into normal football (soccer), this is easily the best of its kind for the 16-bit era
• NBA Jam - Also available on the Mega Drive, dunno which version is better. BOOM SHAKA LAKA!!

My kid used to love one of the Kirby games for the Wii, where the three of us could play at the same time. I can't remember the name of it, but I'm pretty sure it was previously released for the SNES. It was the one with Armor Knight, if I'm remembering the character name correctly.

Lemmings for Amiga had a 2player split screen mode. Goal is to guide the most lemmings (yours and the other players) into your exit.

It's single player, but too good to miss: "Richard Scary's Busy Town" (Genesis) is a fantastic open ended set of mini-games that are fun and accessibible to almost all skill levels of gamer.

Alley Cat Remeow Edition is a fan remake of Alley Cat, an arcade game, with up to 4 players, but it's PC (should still run on that hardware, i hope!)

https://www.youtube.com/watch?v=WIm6oRhyDrM

Goofy Troop

Are you committed to using the R.Pi1? You could emulate on your computer or phone (connected to the TV) to have way more options.

How adept is your little one with games? My 4 year old loves any and all Mario games. He plays sitting on my lap. I celebrate his successes and he passes me the controller when he gets to a section too difficult for him. This is mostly with Mario 3D land (3DS) these days.

R.C. Pro Am

Mega Bomberman (Megadrive) and Super Mega Bomberman (SNES) both have multiplayer mode where players can team up against bots, and the bots have adjustable difficulty (different bot skins have different AI).

Edit: Re violence - you blow each other and bot players up with bombs. Players that die disovle the way Pac-Man does.

Fun-N-Games (Genesis/Megadrive) is mostly single player, but has many mini games accessibile to young gamers.

A c64 emulator? Then basically anything, LOCO maybe?

Snake Rattle and roll! For the NES.

Multiplayer is hard to find for the megadrive but some cutesy games,

• Ecco the dolphin
• James Pond 2 - Robocod
• the sonic games with cute little bunnies
• where in the world is carmen san diego i think was on the md

You know what? Gyromite and Stack-Up, the games made to be played with R.O.B. You play the robot. I don't know many co-op multiplayer games on the NES. Maybe Chip & Dale, or Mario Bros. (not Super, the arcade game - though in 2025, I suggest Kaetekitta(sp?) Mario Bros., the rerelease). Bomberman might have cartoon violence, but I don't think it's going to scar a kid.

On SNES, there's Secret of Mana if you want to try for depth. I forget if any of the sports games let you go co-op. Pocky & Rocky (and other cute 'em ups) might be fun too.

Actually, general suggestion, cute 'em ups. Cotton, Twinbee, Fantasy Zone, Air Zonk, and many of the Parodius incarnations (obviously Sexy Parodius notwithstanding).

Wai Wai World 2 on Famicom emulator. Don't need to know any Japanese to play and it has great cartoony sprites.

Bubble Bobble (NES) is great two player, though you're competing

Buster Bros (PsOne, and probably others) probably one of my top 5 co-op games of all time

Micro Mages (retro despite being released in 2019 because it plays on original NES hardware) probably top co-op of all time for me

There's quite a bit more but have various degrees of violence so won't recommend those (Contra, Heavy Barrel, Silk Worm, Jackal, Life Force, etc)

My Famiclone childhood:

Mario Bros (the first one, with POW block in the middle.) https://en.wikipedia.org/wiki/Mario_Bros.

Battle City, known more by its pirated version name: Tank 1990 https://en.wikipedia.org/wiki/Battle_City

Super Dodge Ball!

Super Baseball Simulator (SNES) is competitive, but can be really chill if the adult player throws easy pitches, and the super powers are hilarious.

Ms. Pac-Man (Genesis) is fully co-op throughout, and has adjustable difficulty by choosing smaller maps.

Dashin' Desperados (Genesis/Mega Drive) is a racing platformer, where the adult can control the difficultly by slowing down or backtracking.

Edit: Cartoon violence - you can freeze each-other, light each-others shoes on fire, and stuff like that. And everyone recovers in cartoon timing, of course.

Kirby Super Star

Nobody's gonna say hide and seek huh? 🤷