If you're comfortable using Python apps in the terminal, here's a business modeling tool set for indie game developers. https://github.com/mikeypdev/runway

You can use the tools to model 12-month financial runways for mobile, pc, and web publishing scenarios. I think the default values for pricing, retention, CPI, etc., are reasonable starting points for a small indie, but you can tune and tweak anything to your liking.

Feedback and PRs are welcome.