I'm still hooked on the Mega Man Legacy Collection compilation of the first six classic Mega Man titles from the Nintendo Entertainment System era, particularly the challenge mode.  In addition to remixed snippets of the original games, some of the challenges send players on a marathon rampage through each game's Robot Master legion (and a grand finale battle where players face all forty-six bosses one after the next). Watch as I plow through the original Mega Man's six Robot Masters in this clip. Yes, I abuse the famous pause trick.