Prince of Persia in JavaScript
Awesome! Takes me back :)My 8 yo son is playing it now, he knows all the modern consoles, but this is challenging him. He is frustrated things are hard from the beginning, jumps don't work right away and he stopped after a few minutes. I remember my perseverance as a kid.I was thinking about that lately, I see my kids don't have this strong motivation as I had, not for anything. Everything works for them and is layed out. For example, when I was young I had a lego technic motor, but the wires sometimes got oxidatid or just broke, and I had to fix it. My son has a new lego set, and the motor always works, except when the wireless remote runs out of battery. 
Same with gaming, it always works, while in the past even getting a game to run could be a challenge on its own. And when he gets stuck in a game he watches a YouTube. No hours of frustration and endless searching and figuring for a solution.I see my kids don't have much of these challenges, everything works for them.Don't know how this will affect them on the long run. Now it's only my observation.