Great questions! I'll just ramble off some bullets:
- PS4 (then 5) for Minecraft (but also iPad). 3DS for Mario Maker 1. Wii and Switch for other Mario games.
- I was shocked that my 6yo, LOVES the NES and SNES Mario games. He loves the challenge and doesn't seem to get discouraged, he just decides its time to stop for a while. The hand-eye coordination is ridiculously impressive.
- Both started around 3-4. Minecraft was the best because by its own nature, they only get exposed to what they can do, but the next tier of challenge is always immediately available. So this lets them grow at their pace. He started learning just how to move around and make a dirt house. These days he's making Redstone machines. I cannot sing Minecraft's praises enough.
- There's something magical about giving a 3 year old a Wii controller with New Super Mario Bros Wii playing, to watch him die about 80 times on the first level, belly laughing every time, then to watch a video from a year later where he just flies through the level. Then to watch him last week getting to 2-2 all on his own in Super Mario Bros. (1989). This is completely beyond anything I was capable of at 6.
- We have a ton of Duplo (and now Lego) and I find that one of the best things is when they begin to mix things together: they'll make Minecraft homes and play scenarios out of Duplo (now Lego). 6yo has a set of Lego in his room and I wake up 2 or 3 times a week to him making some Minecraft thing. "Here's a lever!" "Here's a pressure plate that controls a trap door!" None of it works (yet) but it's his imagination that's growing so well.
- We let them have YouTube Kids. We have to moderate it on occasion, but it's generally good. I love this part because they take a ton of stuff they see others doing and they repeat it. He will show me Mario Maker tricks, or recreate some Lego build (to a 6yo's fidelity).
- We constantly underestimate them. It's why we strive to always have stuff available that's too old for them. Their curiosity will tell all of us when it's the right time for a toy. (My dad busted out a 1960s Meccano set when oldest was 5 and we thought... no way... but he sat methodically for an hour and worked out the tiny nuts and bolts into a car with actual Ackermann steering.
- We also let them have access to a desktop computer with a keyboard and mouse. Watching a 4 year old turn on a PC, log in, open Chrome, get to PBS Kids, and play a game, is a very good way to remember that we constantly underestimate kids.
- Oh and on Mario Maker complexity: I finally understand why Nintendo locks all the features behind "complete these levels to unlock them": It keeps the system super simple... he had so few parts it wasn't hard for him to master them. Then he plays levels, sees new mechanics/parts in action, then gets them. He proudly shows me a new thing he unlocked, then makes a level with it. This is absolutely brilliant self-guided learning. Holy crap, Nintendo. I get you so much better now.
I hope I didn't miss anything. I'm happy to talk lots about this if anyone finds value in it.