> Free
> Game developers (royalties apply after $1 million USD gross product revenue)
> Individuals and small businesses (with less than $1 million USD in annual gross revenue)
> For educators and schools (no revenue limits)
Free for educational purposes means it is not free, since the royalties still apply if the game is released.
Last time I checked, free means free.
Epic is not claiming any rights on your IP.
Mario v1.3 typically means Mario 1 with some patches unless you’re kingdom hearts, so yes that is still the same game. I believe dlc is bundled into the parent game.
Furthermore, many of these devs have been on Unity for many years, not because it was the best, but because it was pretty much the only accessible and modern choice for smaller projects before Godot and other open-source engines were mature enough to release games with.