Knowing you like Nintendo, I'd suggest the NDS, and a flashcart, and just piddling with the games that are tracked here, as far as "randoms", as you usually find a lot of mini games, stuff like that, that you don't have to dedicate serious time to master, like the NES Excitebike
I have an app that has my entire game collection on it. I've filtered it out to only Playstation 1 games and put it on random, pop whatever it shows in the console, and see if it is on the leaderboards or it can be put on the leaderboards. I'm just trying to work my way into the top 10 on that