BRP’s Big Gold Book. From that I can play almost anything. Even though the new book they recently released has better art, the Gold book is better overall imo
I came across this and remembered your thread. Not sure if this is exactly what you’re looking for but it’s certainly a Christian rpg:
https://en.m.wikipedia.org/wiki/DragonRaid
Edit: apologies if it’s already been mentioned.
i do think there is room for indie rpgs. But I think you need to have a good/smart/clever marketing campaign to reach your target audience (which needs to be clearly defined) and pique their interest. Then hopefully develop a small but loyal following and then focus on keeping them.
Without a...
If I were to tinker with any of the d20 systems to make my own off-shoot it would either be:
a) streamline d20 Modern or
b) generalize 4e to make a universal toolkit
But I’m actually working on a 2d6 based game and combing those games for inspiration instead.
Also wanted to point out that as for gaming material goes Monster Vault: Threats to the Nentir Vale has a lot of great stuff. It’s part monster manual, but the description for each monster is not just about the monster (like the Monster Manual), it’s Nentir Vale lore.