max power on 02 March 2009
It's tough to say. Old arcade games were not "hard" so long as you had plenty of quarters. And even then, they just threw hordes of enemies at you so you WOULD pump in more quarters. I'd even say some of them were impossible to beat without getting hit a few times.
And many old console games were hard due to bad level design.
Battletoads, which I love, was ultimately an exercise in memorization. I'm not "better" at the speeder level than I used to be... I just know where all the walls are.
So, to sum up, there is no real answer. I'd say the most "challenging" opponents have always been human. I don't count the computer cuz it can cheat 
