I always felt bad for the devs of the actual Fortnite game. Its clear lots of time and resources were poured into what was actually a pretty good horde style survival/crafting game, then the little BR offshoot came along and now whenever someone says "Fortnite" I just assume they mean BR because no one actually plays the survival game.

I guess they can't complain about the success but it would have to feel at least a little bit demoralizing.

Pretty fleshed-out, pretty feature-rich, pretty long developed - but not pretty good. If it was pretty good we would be talking about the fort construction mode in PUBG now.

Same with Warcraft 3 and DOTA right?

Wasn't Dota a mod? Like, the guy who made it had the intention to make this game (with the help of WC3)

Custom map technically, although the WC3 map editor let you write custom code so the line is kind of blurry.

Sure.

I just had the impression DOTA was made by some guy who wanted to make something like DOTA and Fortnite was made by some people who wanted to make some mix of L4D and Minecraft, but pivoted to doing something like PUBG instead.

lol, serendipity.

As far as I know the regular mode is not free to play.

I only tried it because it was a free alternative to PUBG

The regular mode will be F2P, it's just currently in the "founder's pack" stage of F2P games.