How many copies did RetroArch sell?

An estimated 230k to 373k copies, based on its 10k Steam reviews. This is a labeled estimate from the review count, not exact sales.

How much revenue did RetroArch make?

RetroArch is free to play, so there is no copy-sales revenue to estimate.

How big is RetroArch?

A labeled estimate from the public review count (adjusted for release year), not exact sales. Owner data cross-checked with SteamSpy.

We don't have enough similar games to place RetroArch in its genre yet, so these are its own numbers, not a genre read.

Sizing up your own game? See what its genre can realistically do before you build it.