There are one year to a hundred+ year old kids of all ages playing Game 0 as it is just matching symbols. All ages can catch up in no time if they have fallen behind. You don’t have to join Mensa, but you probably could. Build an index to the symbols and build upon it with usage, pronunciation rules, definitions, ets.. Try the Summer Reading Program at your local library. Early Development, stimulating the mind, and reading are not trivial. Language is the biggest problem you will face in your life. Get it going efficiently and everything else falls right into place perfectly.
Try Game 0 for a month, or maybe more. There is no pressure the student, new reader, non-traditional, or anyone trying a new vocabulary or language can have huge improvements in no time. The beginning games seem like a waste to the experienced reader but it is all about building efficiencies. It seems slow in the time you are learning all the words, but when you will start recognizing them so fast. It is not easy, and it takes a ton of practice. Don’t get discouraged, just realize it is so fun.
Best wishes and keep sleuthing!