Final Fantasy 1, on a NES console.

It's much more tough than all the remake, also alot of annoying stuff like you can't run, there is no automatic target selecting once an enemy is dead, so your characters will just swing at an empty spot, monster are also more powerful and your characters are weaker... yeah.
Graphics and sounds are also crap compared to remake, but that's pretty obvious.
Overall, it's all of the above that makes me play it on NES, brings back alot of memories.

Recently started playing Secret of Mana too, great game!