My brother and I traded our Turbografix-16 (aka PC Engine) for another kid's NES in the early 1990s (we'd been wanting a NES for years, but foolishly chose the mediocre TG16 instead when the opportunity arose; realizing our mistake, my brother fast-talked a friend into a trade - he even threw in some G.I. Joe action figures to sweeten the deal). ANYWAYS, the NES came with a copy of Spiritual Warfare and not much else (SMB1+Duck Hunt, and we had a Cobra Command cartridge laying around that someone had given us at one point).
I don't remember whether I actually beat SW, but I did spend a couple weeks playing quite a ways into the game. The gameplay was actually pretty decent, although it's fair to say that it was a Zelda clone (if a sufficiently creative one). Unfortunately it had no real plot, and you got constantly smacked with cheesy Bible quizzes; these factors turned it into a bit of a repetitive slog through various "environments" like a park, a downtown area (don't go in the bars! That's sinful!), an airport, etc.
The interesting thing is that the developer Wisdom Tree actually started out as a secular company named Color Dreams. They decided to enter the Christian games niche for some reason, converting some of their existing secular games into Christian ones. They did surprisingly well, and I remember seeing their games in Christian bookstores at malls when my mom dragged us through them (I noticed everything video game related when I was a kid, no matter where I was; video and computer games have been a life-long interest for me).