I just 100% completed Super Mario Bros. Deluxe for the first time.
I'm now convinced that DX is definitively the best version of this game.
It has so many different varieties of goals to complete besides just
"beating the game", making you see this game in a whole different light
than what you are normally used to when you just focus on surviving till
the end or getting to the end as fast as possible with warp points.
The Challenge Mode is all of the individual levels of the main game with
extra goals added, including finding the hidden Yoshi Egg and 5 red
coins that were added to each level. There's also the individual level
high score goals. These target scores aren't insanely unreasonable or
anything, but they really require you to practice the level and gain a
much more in-depth understanding of the level's construction than you
would normally get from just beating the level normally. You need to
figure out all the ways you can combo enemies and collect the coins and
hidden 1ups/powerups for extra points while still beating the level
quickly for the timer bonus. It makes you think "hmm, would it be better
to take this vine/pipe to a shortcut area with coins, or would it be
better to take the normal route and kill all the enemies along the
way?"... stuff that you would never think of when playing the game
normally on the NES version...