I've never played a ROM of anything pertaining to SMW because, for the better part of the past 20 years or so, I've always had it on hand, either by way of the original SNES cartridge, or the slightly re-tooled game-on-the-go GBA version.
However, I do remember one downloadable version of Super Mario, and as far as I know, it's still a pretty good mildly-entertaining PC diversion, and it's still highly-acclaimed by some.
Super Mario Forever
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also, there's this:
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The Sheriff and His Deputy, by Charity Ryan
[
superpunch.]