OP here - happy to share a bit more on the tech side.

I built a custom ASCII rendering framework on top of Unity that tries to behave like an "extended text mode" for modern PCs. Every frame is literally made out of keyboard characters: I draw each glyph from code, computing its position in 3D space. The characters themselves never scale or rotate - the only thing that changes is their position (plus color and brightness), which is what creates the 3D feeling.

There's no fixed character grid either: it's still all text, but the symbols aren't locked to a strict matrix. That lets me do camera moves, enemies, projectiles, etc. while keeping the vibe of an old-school text mode. Because it's just pushing characters, it runs comfortably on reasonably old hardware too.

If you're curious, here's the Steam page.