If puzzle games such as the recent Dr Mario NES hack, mentioned previously, is just not your thing, then how about a full English translation of the NES sci-fi dungeon crawler ' Shadow Brain ', which was only just released by Aishsha and Stardust Crusaders. As noted by Romhacking, Shadow Brain looks very much like Megami Tensei, and the game when originally released actually came with a VHS tape that provided the backstory. Although they don't have the VHS tape on hand, they have provided a full translation in the archive.
Do note however, the video above is from the preview translated version but it does give a good indication of what the game is about, how it plays and the types of evil baddies you are likely to come across in the full translation that was released today.
Links : 1) Source