Crystalis has some good aspects to it, and at the start it seemed like an interesting take on Zelda-esque gameplay with some RPG elements. The intro is also cool as hell, and it has some great music and fun sprite art in places. Unfortunately, the dungeon design is extremely underwhelming, and fighting enemies becomes tedious quickly.

You have a normal Zelda 1 sword stab, but you also have abilities you can charge, and several different elements you can attack with as the game goes on. Eventually every enemy can poison or paralyze you if you touch them, so the game quickly becomes "ok stop and charge your thing, shoot it, ok now go back and charge it, shoot it again, ok do it again". The game also does this I cannot stand in games where it just sort of expects you to know what order to do things in, especially when there is no way you could figure it out. This alongside the annoying combat eventually got to me and I couldn't be bothered to continue. This is the kind of NES game you play after you've played all of the good NES games.