My dad got me into gaming, we used to play the original Super Mario Bros until we were able to beat it multiple times over in one sitting. He couldn't keep up with newer games, more buttons, more complex controls, etc. and lost interest. I was either reading books or playing videogames from the time I was able to do either, and honestly not much has changed. The first game I remember beating totally on my own and feeling a huge sense of accomplishment was Mario 3.
I also had some eyesight problems when I was 6 or 7 and my optometrist actually told my parents that gaming would be good to strengthen my eyes and specifically eye-hand coordination. I don't think they realized I'd still be doing it ~25 years later.
So I need a Doom recommendation. If I only play one Doom game...what one and what version? I have never played any of them much. I actually remember renting it on SNES back in the day but did not get far...Doom64 looks interesting to me but is it the best Doom (or console Doom) experience?
Doom 64 is good (and the remaster did a great job making it playable on modern systems) but I wouldn't recommend it for a starting point.
The original Doom is still a lot of fun IMHO and is a testament to good game design, there's a reason there is still a huge community of people who make new WAD files and still play it. Doom 2016 is one of my favorite games of this generation, and a great starting point too. The 'Slayers Collection' is only $13 which is only $3-4 per game for the ones included. Doom 2016 is on sale for $10 by itself, so for $1 each you can get the older games too. Just do it.