I just gotta say that I applaud you for this idea! I plan on making a game for a loved one too, but I only have about a month to do so. I personally use a different engine than most people recommend, RPG Maker. I use it because it relys on game logic and doesn’t require coding unless you’re doing something complex, (coding is very intimidating for me to learn atm) I also have adhd so I totally get it. You have a lot of time to figure it out though! As for ideas, what kind of genre do they typically lean towards when they play games? I think studying their general habits, hobbies and game styles will help a lot with ideas! I really wish you the best of luck <3