Technically not free, but rather pay what you want. You can still grab the original version from the official website.

Iirc the Plus version was originally made because of consoles. The original game was very PC specific, as you needed to

Spoiler

touch the files in the game’s install folder

to be able to complete it, and to find some otherwise hidden content. That’s of course not possible on consoles…

I haven’t played the Plus version, because I think that having an in-game

Spoiler

computer desktop

is a massive spoiler. Also, I think it changes the perspective a lot, as there’s an intermediate layer in-between that you don’t have if you

Spoiler

directly interact with the game, and have the game running on your own PC instead of a simulated interface.

But, as said, I haven’t played it, so it might not actually feel as different to the original game than I fear it does.