Ask HN: How do I find work making something new?

I'm in my 6th year as a developer. I have technically achieved the status of senior, although I don't feel like one, in part because the vast majority of my work has been making gnarly incremental changes on huge, complicated legacy applications. This is fine and worthy work, but I want to break ground on something. I got to put ~20 hours into a personal project over the holidays and it was the most I've enjoyed programming in years. I don't want to sit and stare at a code base and figure out what every dangling wire does, only to have a more tenured colleague point out that I missed something, and then start over again afterward in a new, equally storied part of the codebase. Am I naive? Is this just the job? Will I just have to risk it in a startup? I don't care about making oodles of money, I want to lose myself in work I can do confidently. I want a chance to call the shots on the design of a project--and then implement it, and maintain/improve it--instead of being a clueless code monkey. I could feel my productivity dropping before the holidays, and now that I'm back (and behind deadline) I'm starting to feel the same sinking feeling I had before.

How do I go about finding work like that? What can I expect?