Mega Man 2 for the Tiger handheld system. An abomination in every sense of the word. But by golly, it was the most "convenient" way to take the game on-the-go in 1990.
Above is the commercial for this dubious imitation, which tries way to hard to make the game appear more than it actually is. It's a neat little blast from the past, one which I bet fewer Mega Man fans are familiar with.
Thanks to SuperMega233 for helping me dig this one up!